WO2018061032A1

WO2018061032A1 - Twelve-armed hexaphenylbenzene-based giant supramolecular sponge for molecular inclusion and process for preparation thereof

Info

Publication number: WO2018061032A1
Application number: PCT/IN2017/050437
Authority: WO
Inventors: Gangadhar Jessy SANJAYAN; Suresh MADHU
Original assignee: Council Of Scientific & Industrial Research
Priority date: 2016-09-30
Filing date: 2017-09-29
Publication date: 2018-04-05

Abstract

The present invention discloses twelve-armed hexaphenyl benzene (HPB)-based giant supramolecular sponges of formula (I) for molecular inclusion and process for preparation thereof.

Description

TWELVE-ARMED HEXAPHENYLBENZENE-BASED GIANT SUPRAMOLECULAR SPONGE FOR MOLECULAR INCLUSION AND PROCESS FOR PREPARATION THEREOF FIELD OF THE INVENTION:

The present invention relates to twelve-armed hexaphenyl benzene (HPB)-based giant supramolecular sponges of formula (I) for molecular inclusion and process for preparation thereof. BACKGROUND AND PRIOR ART OF THE INVENTION:

Crystal engineering has become an extremely promising area of science which seeks to predict and control over the structure and properties of crystalline materials. Such materials are intensively attractive for gas storage, separation, catalysis, proton conductivity, etc. These applications highly depend on non-covalent interactions between host and guests. Molecular- recognition and assembly of host-guest molecules using multivalent interactions have become an important component of supramolecular synthesis. Hence, multivalency can be harnessed to organize molecules into functional materials through non-covalent forces.

According to supramolecular chemistry, the state of a system can be regulated by the mixing of different components which are having very strong interaction with each other resulting in the formation of super molecules. The physical properties of super molecules are entirely different from the original discrete molecules. Among many types of supermolecules, host- guest systems are of current interest due to their potential applications in ferro-electric, catalysis, drug delivery and sensing, gas storage and separation, etc. These host-guest systems can be classified according to their topologies into types: intramolecular and extramolecular host-guest aggregates. In intramolecular systems (cavitate), the cavity is already inherent in their molecular structure, as in calixarenes, pillararenes, cucurbiturils, and shape-persistent organic cage compounds. In contrast, extramolecular inclusion (adducts) arises purely based on aggregation through noncovalent forces such as charge transfer and directional H-bond, etc., but is not inherent to the isolated molecular geometry of the host. Although both the intra and extramolecular host-guest systems are well explored in the formation of inclusion complexes in the solid state, hybrid of these mixed intra-extra molecular aggregates using a single host molecule are rarely encountered in the literature. It is possible to show such a hybrid host-guests systems to uptake wide range of guest molecules by using a single host, which can exhibit supramolecular isomerism in its solid state. To design such a host molecule which would act as a supramolecular sponge, the following structural features should be considered: 1) easily modifiable multivalent functional groups, 2) backbone rigidity with aromatic residues, and 3) non-covalent forces such as hydrogen bond, van der Waals force, etc.

Article titled "Molecularly tethered amphiphiles as 3-D supramolecular assembly platforms: Unlocking a trapped conformation" by Christopher G. Clark et al. published in Journal of chemical Society, 2009, 131, 8537-8547 reports a fluorous biphasic hexa(3,5-substituted- phenyl)benzene (HPB), analogous to semi fluorinated alkanes, was synthesized such that precise chemical and orthogonally directed, supramolecular placement of amphiphilic side chains at their bulk density was achieved.

Article titled "Hexaphenylbenzenes as potential acetylene sponges" by Eric Gagnon et al. published in Organic Letters, 2010, 12(2), 380-383 reports acetylene sponges can be created by taking advantage of the nonplanar geometry of hexaphenylbenzenes and the special capacity of the central aromatic ring to engage in C(sp)-H · · ·π interactions reinforced by secondary C(sp2)-H · · π interactions, as revealed by X-ray crystallographic studies and DFT calculations.

Article titled "Organic radical ions" by Nadeem Khan et al. published in Electron Paramagnetic Resonance, 2004, Volume 19, pp 82-115 reports hexaphenyl benzene and tetraphenylmethane have been reported as plat-forms for the preparation of multi-centred electron donors that are bearing six and four redox active centres. These extended electron donors undergo multiple electron loss in a single step (at a constant potential) to afford highly charged cation-radical salts of 7 and 8, that are remarkably robust and are isolated in pure form. These nanometre- size cation radical salts are shown to act as efficient 'electron sponges' towards a variety of electron donors.

Article titled "Enclathration of morpholinium cations by Dianin's compound: salt formation by partial host-to-guest proton transfer" by Gareth O. Lloyd et al. published in Chemical Communication, 2005, pp 4053-4055 reports enclathration of relatively large guest molecules such as morpholine (2, Scheme 1). Slow evaporation of a concentrated solution of Dianin's compound in morpholine yielded crystals suitable for X-ray structural analysis. The asymmetric unit consists of six molecules of Dianin's compound (four neutral and two deprotonated), as well as two morpholinium cations. Structures with such large values of Z9 are relatively unusual and generally warrant investigating the possibility of a misassigned space group.

There is an ever increasing need for developing smart materials which can absorb large amounts of guest's molecules in their molecular lattice. Such systems will be of considerable use in material science, for instance: proton conductivity, channelizing of guest molecules according to their polarity and gas adsorption. Furthermore, such systems would also help in solving the crystal structure of challenging guest molecules, by trapping them in the crystal lattice of the host.

OBJECTIVE OF THE INVENTION:

The main objective of the present invention is to provide twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges of formula (I) for molecular inclusion.

Another objective of the present invention is to provide a process for preparation of twelve- armed hexaphenyl benzene (HPB)-based supramolecular sponges of formula (I) for molecular inclusion.

Still another objective of the present invention is to provide twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges of formula (I) shows unprecedented ammonia inclusion based purely on hydrogen bond interactions (without any acid base interaction). Yet another objective of the present invention is to provide twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges of formula (I) with very high thermal stability

(TGA 300-400° C).

SUMMARY OF THE INVENTION:

Accordingly, the present invention provides a twelve-armed hexaphenyl benzene (HPB)- based supramolecular sponges of Formula (I).

Formula (I) wherein R=OR\ Br, CI, F, R'R", HNH₂, Wherein R' and R" is independently selected from the group consisting of hydrogen, alkyl, aryl, carbocycle, aromatic or non-aromatic heterocycle, metal and peptide.

In another embodiment of present invention said sponge shows thermal stability, in the temperature range of 300-400 ⁰ C.

In another embodiment of present invention provides a composition comprising supramolecular sponge of Formula (I) and a guest molecule.

In another embodiment of present invention said sponge encapsulate the guest molecules in voids of its crystal lattice through the co-operative interplay of multivalency, noncovalent forces, and backbone rigidity.

In another embodiment of present invention the guest molecule is selected from the group consisting of DMSO, DMF, NMP, methanol, ethanol, hexane, HCOOH, [12]-crown-4 ether, Benzene, Salicylaldehyde, (+/-)Styreneoxide, Toluene, Pyridine, Aniline and N- methylaniline.

In another embodiment of present invention a process for the preparation of said supramolecular sponge of Formula (I) as claimed in claim 1, wherein said process comprising the steps of:

a) adding iodine to a stirred solution of sodium periodate in acid at the temperature ranging from 36°C to 40°C followed by stirring for the time period ranging from 30 to 45 mins; further adding dialkyl isophthalate (1) and continuing the stirring for the time period ranging from 12 to 14 hours to afford dialkyl-5-iodoisophthalate (2) ; b) one pot sequential Sonagashira coupling comprising adding trimethylsilylacetylene (TMSA) and dry amine base to a stirred solution of dialkyl-5-iodoisophthalate (2), palladium catalyst, copper cocatalyst in dry solvent under an inert atmosphere; stirring resulting mixture at the temperature ranging from 25°C to 30°C for the time period ranging from 3 to 4 hours to afford Sonagashira coupling product (one side aryl coupled TMSA);

c) further adding Tetra-n-butylammonium fluoride (TBAF) dropwise into said Sonagashira coupling product drop wise for 3 to 4h, further stirring reaction mixture at the temperature ranging from 25°C to 30°C for the time period ranging from 12 to

14 hours to afford compound (3);

d) refluxing the reaction mixture of compound (3) and trimerisation catalyst in suitable solvent for a time period ranging from 6 to 7 hours to afford compound (4);

e) heating reaction mixture of compound 4 and amination agent in a suitable solvent at the temperature ranging from 80°C to 90°C for a time period ranging from 12 to 14 hours to afford compound of Formula (I), said reaction is carried out in steel bomb. In another embodiment of present invention said acid of step (a) is selected from sulphuric acid (H₂S0₄), Oleum.

In another embodiment of present invention said dialkyl isophthalate of step (a) is selected from dimethyl isophthalate and diethylisophthalate.

In another embodiment of present invention said amine base of step (b) is selected from triethylamine and diisopropylethylamine.

In another embodiment of present invention said palladium catalyst of step (b) is selected from Bis(triphenylphosphine)palladium(II) dichloride and

Tetrakis(triphenylphosphine)palladium(0).

In another embodiment of present invention said copper cocatalyst of step (b) is copper iodide (Cul).

In another embodiment of present invention said dry solvent of step (b) is selected from tetrahydrofuran (THF) and dioxane.

In another embodiment of present invention said trimerisation catalyst of step (d) is selected from Dicobalt octacarbonyl (Co₂(CO)₈) and PdCl₂(CH₃)₂] .

In another embodiment of present invention said solvent of step (d) is selected from dioxane and toluene.

In another embodiment of present invention said amination agent of step (e) is selected from methanolic methylamine, methanolic ammonia and hydrazine hydrate.

In another embodiment of present invention said solvent of step (e) is selected from dioxane, methanol, and tetrahydrofuran. In an embodiment, the present invention provides a process for the preparation of twelve- armed hexaphenyl benzene (HPB)-based supramolecular sponges of formula (I) for molecular inclusion. Abbreviation:

HPB: Hexaphenyl benzene

TGA: Thermal gravimetric analy

DMSO: Dimethyl sulfoxide

DMF: Dimethylformamide

NMP: N-Methyl-2-pyrrolidone

HCOOH: Formic acid

DCM: Dichloromethane BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1: Structural characteristics of multivalent hydrogen-bonded hexaphenylbenzene (HPB) -based supramolecular sponge.

Figure 2: Crystal packing of ester 4 and methylamide 5. a) well-packed crystal structure of 4 crystallized from DCM alone; b) DMSO-trapped crystal structure of 4 crystallized from DCM-DMSO; c) trapped guest molecules (water) in between the 2D sheet of 5 in H20@HPB(CONHMe)i2 and d) trapped guest molecules (water and acetone) in between the 2D sheet of 5 in Acetone.H₂0@HPB(CONHMe)i₂.

Figure 3: Crystal packing of compound 6 with the inclusion of various guest molecules, a) DMSO@HPB(CONH₂)i₂ b) DMSO.H₂0@HPB(CONH₂)i₂ c) NMP@HPB(CONH₂)i₂; d) DMF@HPB(CONH₂)i₂; e) HCOOH@HPB(CONH₂)i₂); f) DMF.HBr@HPB(CONH₂)i₂. Figure 4: Polarity-dependent channelization of guest molecules such as methanol, ethanol, DMSO, hexane in compound 6 (DMSO.MeOH.C₂H₅OH.Hexane@HPB (CONH₂)i₂).

Figure 5: Trapped ammonia (spacefill), dioxane (ball&stick) and methanol (ball&stick) in the crystal lattice of compound 6 (MeOH.Dioxane.NH₃@HPB(CONH₂)i₂.

Figure 6: Visual and analytical evidence for the presence of ammonia in crystal system MeOH. Dioxane. NH @HPB(CONH₂)i₂ with pH paper color test of crumbled crystals: a) negligible color change at RT; b) slight blue color at 60°C; c) blue color change at 68°C; d) intense blue color at above 70°C; e) infra-red (IR-ATR mode) spectrum of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂, fresh and after heating at 40 °C for 12h; f) thermo gravimetric analysis (TGA-Thermogram) of fresh crystals of MeOH.Dioxane.NH₃@ HPB(CONH₂)₁₂. Figure 7: Superposition of the X-ray structure of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂) with DFT optimized structure.

Figure 8: Trapped ammonia, methanol, urotropine, reaction equilibrium intermediate 2- azaallenium with counter ion chloride in the crystal lattice of compound 6 (MeOH.Urotropine.NH₃.aminomethyleneimine.Cr@HPB(CONH₂)i₂).

Figure 9: Superposition of the X-ray structure (blue) of MeOH. Urotropine. NH₃.2- azaallenium.Cr® HPB(CONH₂)i₂ with its DFT optimized structure.

Figure 10: pH paper test: a) Gradual release of Ammonia from MeOH.Dioxane.NH₃@HPB(CONH₂)i2 at different temperatures.

Figure 11: Representative SEM images of crumbled sample of MeOH.Dioxane.NH3 @HPB(CONH2)i₂.

Figure 12: Formation of various HPB based multivalent supramolecular sponge-cavitates a) [12]-crown-4@HPB(COOMe)i₂; b)Benzene@HPB(COOMe)i₂; c)

Salicylaldehyde@HPB(COOMe)i₂; d) (+/)Styreneoxide@HPB(COOMe)i₂; e) Toluene@HPB(COOMe)i₂; f) Pyridine@HPB(COOMe)i₂; g) Aniline @ HPB (C OOMe) ₁₂ ; h) N-methylaniline @ HPB (COOMe)

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.

The present invention provides a twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges of Formula (I).

wherein R=OR\ Br, CI, F, R'R", HNH₂, Wherein R' and R" is independently selected from the group consisting of hydrogen, alkyl, aryl, carbocycle, aromatic or non-aromatic heterocycle, metal and peptide. In another embodiment of present invention said sponge shows thermal stability, in the temperature range of 300-400 ⁰ C.

In a preferred embodiment, said twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges of Formula (I) is selected from tolane etera ester.

In an embodiment, the present invention provides a rationally designed, giant multi-armed hexaphenylbenzene (HPB)-based supramolecular sponge of formula (I) which can encapsulate a variety of guest molecules in the voids of its crystal lattice through the cooperative interplay of multivalency, noncovalent forces, and backbone rigidity.

In a preferred embodiment, said twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges of formula (I) shows unprecedented ammonia inclusion based purely on hydrogen bond interactions (without any acid base interaction).

In another preferred embodiment, said twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges of formula (I) shows very high thermal stability (TGA 300-400° C). In still another preferred embodiment, said guest molecule is selected from dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-Methyl-2-pyrrolidone (NMP), methanol, ethanol, hexane, HCOOH [12]-crown-4 ether, Benzene, Salicylaldehyde, (+/)Styreneoxide, Toluene, Pyridine, Aniline and N-methylaniline.

In another embodiment, the present invention provides a spongy system which shows unprecedented inclusion of ammonia and segregation of the guest molecules according to their polarity in the lattice.

In a preferred embodiment, said molecular sponge is able to channelize guest molecules based on their polarity.

Still in another embodiment, the present invention provides a spongy system which has been used to obtain the crystal structure of a hitherto unproven 2-azaallenium intermediate, which is involved in aminomethylatuion of activated arenes.

The present invention provides a rationally designed novel class of axially substituted multivalent hydrogen bonded hexaphenylbenzene derivatives (HPB) which have been shown to exhibit supramolecular isomerism in the solid-state, via the co-operative interplay of multivalent hydrogen bonding and backbone rigidity of HPB with respect to guests.

In the propeller shaped HPB, the central benzene ring is connected to six phenyl rings aligned perpendicularly. The highly substituted HPB featuring twelve hydrogen bonding functional groups evenly projected in opposite planes, with respect to the central benzene ring, assumes a characteristic propeller shape (Figure 1). Some of the multivalent hydrogen bonding sites get involved in network formation through intermolecular hydrogen bonding and the remaining participate in the capture of the guest molecules. Comparison of the HPB ester 4, primary amide 6 and secondary amide 5, clearly suggests the key role played by the primary amide groups in the formation of hybrid cavities in the solid state.

Yet in another embodiment, the present invention provides a process for the preparation of twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges of formula (I) for molecular inclusion comprising the following steps:

a) adding iodine to a stirred solution of sodium periodate in acid at the temperature ranging from 36°C to 40°C followed by stirring for the time period ranging from 30 to 45 mins; further adding dialkyl isophthalate (1) and continuing the stirring for the time period ranging from 12 to 14 hours to afford dialkyl-5-iodoisophthalate (2) ;

b) one pot sequential Sonagashira coupling comprising adding trimethylsilylacetylene (TMSA) and dry amine base to a stirred solution of dialkyl-5-iodoisophthalate (2), palladium catalyst, copper cocatalyst in dry solvent under an inert atmosphere; stirring resulting mixture at the temperature ranging from 25°C to 30°C for the time period ranging from 3 to 4 hours to afford Sonagashira coupling product (one side aryl coupled TMSA); further adding Tetra-n-butylammonium fluoride (TBAF) dropwise into said Sonagashira coupling product drop wise for 3 to 4h, further stirring reaction mixture at the temperature ranging from 25°C to 30°C for the time period ranging from 12 to 14 hours to afford compound (3);

c) refluxing the reaction mixture of compound (3) and trimerisation catalyst in suitable solvent at the temperature ranging from 110-120°C for the time period ranging from 6 to 7 hours to afford compound (4);

d) heating reaction mixture of compound 4 and amination agent in a suitable solvent at the temperature ranging from 80°C to 90°C for the time period ranging from 12 to 14 hours to afford compound of Formula (I), said reaction is carried out in steel bomb.

In preferred embodiment, said acid of step (a) is selected from sulphuric acid (H₂S0₄), Oleum.

In another preferred embodiment, said dialkyl isophthalate of step (a) is selected from dimethyl isophthalate, diethylisophthalate. In still another preferred embodiment, said amine base of step (b) is selected from triethylamine, diisopropylethylamine.

In yet another preferred embodiment, said palladium catalyst of step (b) is selected from

Bis(triphenylphosphine)palladium(II) dichloride [PdCl₂(PPh₃)₂],

Tetrakis(triphenylphosphine)palladium(0) [Pd(PPh₃)₄] .

In still yet another preferred embodiment, said copper cocatalyst of step (b) is selected from copper iodide (Cul).

In still yet another preferred embodiment, said dry solvent of step (b) is selected from tetrahydrofuran (THF), dioxane.

In still yet another preferred embodiment, said trimerisation catalyst of step (c) is selected from Dicobalt octacarbonyl (Co₂(CO)₈), PdCl₂(CH₃)₂.

In still yet another preferred embodiment, said solvent of step (c) is selected from dioxane, toluene.

In still yet another preferred embodiment, said amination agent of step (d) is selected from methanolic methylamine, methanolic ammonia, hydrazine hydrate.

In still yet another preferred embodiment, said solvent of step (d) is selected from dioxane, methanol, tetrahydrofuran (THF).

The above process is shown in following scheme 1:

2 (90%) 3 (68%)

Wherein R= OH, Br, CI, F, NH₂, NHNH₂, O-alkyl, O-aryl, O-carbocycle, O-heterocycle, O- metal, NH-alkyl, NH-aryl, N-carbocycle, N-heterocycle NH-peptide

Scheme 1

Still yet in another embodiment, the present invention provides crystal Structure investigations of HPB ester and inclusion of guest molecules.

Figure 1 shows m-substituted functional groups projected in two planes for increased assembly and cavities. Due to the presence of functional groups up and down of the HPB as shown Fig. l intrinsic cavities are existing. Multivalent (12 arms) functional groups are increasing extensive intermolecular assembly to tune cavities and to hold guest molecules using non-covalent forces. Aromatic framework offers thermal stability and conformationally restrained phenyl arms are holding guests tightly.

The HPB ester 4 [HPB(COOMe)i₂] could be readily crystallized from solvents such as dichloromethane and a mixture of dichloromethane-dimethylsulfoxide (DCM-DMSO). Analysis of the crystal structure revealed that there is no inclusion of guest molecules when 4 is crystallized from dichloromethane alone, whereas the crystals obtained from a mixture DCM and DMSO showed inclusion of DMSO in the cavity formed by the assistance of phenyl rings and the ester groups. This structural observation suggested that the intrinsic porosity in 4 is solvent depended and that a mere presence of phenyl rings and multiple ester groups appended on a rigid template are not sufficient enough to endow 4 with efficient molecular sponge-like capability due to the absence of hydrogen bonding (Figure 2 a, b and Fig 12 a-h).

The crystals of methylamide 5 showed inclusion of good number of guest molecules. The guest molecules (water and acetone) are trapped in between the 2D sheet formed through self-assembly of host molecules in the respective crystals H₂0@HPB(CONHMe)i₂ and Acetone.H₂0@HPB(CONHMe)i₂. Most of the guest molecules are located in the cavities created by intermolecular assembly of the hosts, though the intrinsic cavities within the molecules (Figure 2 c,d) could hold relatively less number of guests. These observations imply that the secondary amide 5 is having improved spongy nature than its corresponding ester 4 devoid of H-bonding donor-accept groups.

The primary amide derivative 6 having plenty of hydrogen bond donor- acceptor sites in its structure undergoes extensive self-assembly (aggregation) and is insoluble in many of the common organic solvent systems at ambient conditions. Fortunately, 6 dissolved in hot DMSO from which it quickly crystallizes. These observations suggested that the presence of strong intermolecular hydrogen bonding facilitates the formation of crystals of 6 DMSO@HPB(CONH2)i₂ with the inclusion of large number of DMSO as guest molecules in the crystal lattice (Figure 3a). 6 captures large number of many other guest molecules such as: DMSO-H₂0 (Figure 3b), N-methyl-2-pyrrolidone (NMP, Figure 3c), N,N-dimethyl formamide (DMF, Figure 3d), formic acid (HC0₂H, Figure 3e) and N,N-dimethylformamide hydrogen bromide complex (DMF.HBr, Figure 3f).

Another interesting property of compound 6 is the ability to create two types of voids in the crystal due to the presence of hydrophobic (HPB intrinsic cavity) and hydrophilic (CONH₂ functional group, extrinsic cavity) regions in its structure, helping compartmentalization of polar and non-polar guest molecule in the respective voids of the sponge. This property is found when compound 6 is crystallized under solvothermal method with a mixture of polar and non-polar solvents such as DMSO, ethanol, methanol and hexane. Analysis of the crystal structure revealed that the polar and non-polar guest molecules trapped in the HPB network are compartmentalized according to their polarity. The polar guest molecules such as DMSO, MeOH and C₂H₅OH are trapped in the extrinsic cavity (hydrophobic) formed through the assistance of multivalent-hydrogen bonds whereas, non-polar guest molecules are trapped in the intrinsic cavity - formed through backbone rigidity of HPB, as shown in Figure 4.

Still yet in another embodiment, the present invention provides ammonia trapping in the organic frame work.

The twelve armed HPB system is able to trap ammonia in its crystal lattice of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂. Crystals of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂ are prepared under hydrothermal conditions, in the course of the reaction while converting 4 to 6. This experiment has been repeatedly standardized using a mixture of highly saturated methanolic ammonia and dioxane in stainless steel covered autoclave at 80-90 °C to obtain 6 as block- shaped crystals. A suitable single crystal is mounted for the data collection and the crystal structure revealed the presence of ammonia, methanol and dioxane as guests in the crystal lattice of 6 (Figure 5.).

It is well-known that ammonia exists as a gas at ambient temperature due to the lack of hydrogen bonding acceptor sites. However, when the external molecules provide suitable hydrogen bonding acceptor sites, ammonia molecules may get entrapped within the lattice of the complex. The same concept works here to trap ammonia in the crystal lattice of 6, wherein the twelve arms of the HPB are involved in the formation of cavities as well as to trap the guest molecules, through noncovalent forces. The twelve arms of the HPB are symmetrically arranged in such a way that if the guest molecules try to escape from one of the arms, the other arms may readily catch and hold them in the crystal lattice. Analysis of the crystal data further revealed that HPB holds sixteen ammonia, eight dioxane and sixteen methanols per unit cell.

Crystals MeOH.Dioxane.NH₃@HPB(CONH₂)i₂ are seen to be unstable under ambient conditions since they crumble slowly, emitting ammonia. Ammonia bubbles can be seen evolving under a microscope. However, crystals have been found to be stable in the methanolic ammonia mother liquor, and to a certain extent in silicone oil. Crystals also quickly crumble when suspended in solvents such as methanol. The crumbled crystals do not emit ammonia significantly at ambient conditions, as evident from a negative pH paper test (figure 6a). However, when the crumbled crystals are heated, ammonia evolution is noticed, as evident from a positive pH paper test (figure 6b-6d). This experiment reveal that the bound ammonia is having strong interaction in the crystal with host molecules under ambient conditions. Upon heating, ammonia got released from the system due to the destruction of intermolecular interactions between host-guest and guest- guest molecules. Moreover, the presence of umbrella type mode band at 1015 cm^"1 and broadening of the IR band about 3100-3500 cm^"1 in fresh crystals of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂ when compared with sample heated at 40 °C, supports the presence of ammonia in the system (Figure 6e).

Hence, the weight loss about 8% at the temperature range 30-90 °C in thermogravimetric analysis (TGA) attributed to slow release of ammonia and other guest molecules, which reveals that the guest holding ability of compound 6 is temperature-dependent (Figure 6f). Repeated single crystal x-ray analysis of MeOH. Dioxane. NH₃@HPB(CONH₂)i₂ showed that there is no significant change in the position and electron density of ammonia confirming the presence of ammonia site is fixed in the lattice of all similar type of crystals. Furthermore, DFT energy minimized model of MeOH. Dioxane. NH₃ @HPB(CONH₂)i₂ supports the favorability of the system (Figure 7).

Still yet another embodiment, the present invention provides mechanistical investigation of urotropine formation/decomposition by trapping of reaction intermediates.

The ability of HPB(CONH₂)i₂ (6) to entrap several guest molecules led us to investigate the reaction mechanism for the formation/decomposition of urotropine in basic pH under hydro thermal condition. Although literature precedence on the formation/decomposition mechanism of urotropine in the solution state is plenty, evidence are seldom provided - particularly by single crystal studies. Upon replacing dioxane with DCM in the conversion of compound 4 to 6, inventor have found the presence of urotropine along with 2-azaallenium (CH₂=N⁺=CH₂) intermediate bearing chloride (CI ) counter ion, ammonia and methanol in the crystal lattice (Figure 8).

2-azaallenium is believed to be an equilibrium structure of one of the intermediates which is formed in the formation/decomposition of urotropine at basic pH. This is for the first time that 2-azaallenium intermediate has been characterized using single crystal X-ray structure. It is noteworthy that this intermediate has been proposed to be involved in a number of formylation reactions of activated arenes, including the aminomethylation of tannins. 2- Azaallenium intermediate has only been characterised, so far, through spectroscopic techniques such as NMR by the stabilisation of counter ion sulphate. Further, DFT energy minimised model of MeOH. Urotropine. NH3.2-azaallenium.Cr@HPB(CONH₂)i₂ supports the favorability of the system (Figure 9).

Still yet in another embodiment, the present invention provides different applications of HPB of formula (I) like gas storage, channelization of small molecules for separation, catalysis, structural determination challenging guest molecules, chiral discrimination, artificial receptor for guest molecules.

Examples Following examples are given by way of illustration therefore should not be construed to limit the scope of the invention.

Example 1: General Methods:

Unless otherwise stated, all the chemicals and reagents were obtained commercially. Dry solvents were prepared by the standard procedures. Analytical thin layer chromatography was done on pre-coated silica gel plates (Kieselgel 6OF254, Merck). Unless otherwise stated column chromatographic purifications were done with 100-200 mesh silica gel. NMR spectra were recorded in CDCb on AV 200 MHz, AV 400 MHz or AV 500 MHz spectrometers. All chemical shifts are reported in δ ppm downfield to TMS and peak multiplicities as singlet (s), doublet (d), triplet (t), quartet (q), broad singlet (bs), and multiplet (m). IR spectra were recorded using CHCb on Shimadzu FTIR-8400 spectrophotometer or FT-IR Bruker optics ALPHA-E spectrometer equipped with universal ZnSe ATR (attenuated total reflection) accessory or using a diamond ATR (Golden Gate) in the 400-4000 cm -1 region.. Thermogravimetric analysis was done on Perkins-elmer (STA) 6000. Melting points were determined on a Buchi melting point B-540. MALDI-TOF/TOF mass spectra were obtained from ABSCIEX TOF/TOF™ 5800 mass spectrometer.

Example 2: Synthesis of Dimethyl-5-iodoisophthalate (2):

Iodine (18.29 g, 72 mmol) was added to a stirred solution of sodium periodate (8.8 g, 41 mmol) in 110 mL 96% sulfuric acid at 36 °C under argon atmosphere. The resulting mixture was stirred for 30 minutes. To this mixture was added dimethyl isophthalate 1 (20 g, 103 mmol) and stirring was continued for 12 h. After completion of the reaction, the reaction mixture was poured into the mixture of crushed ice and dichloromethane (DCM). The organic layer was then separated and the aqueous layer repeatedly washed with dichloromethane. The collected organic layers were carefully washed with sodium bicarbonate, sodium thiosulfate and brine respectively. The combined organic layers were collected and dried over anhydrous sodium sulfate followed by evaporation to afford compound 2 as colorless crystalline material (30 g, 91 %) which was used without further purification for the next step, mp: 99-101 °C; TLC (Ethyl acetate:pet ether, 5:95 v/v): R_f = 0.3; IR (CHC1₃) cm^"1: 3023, 2955, 1727 (C=0), 1569; 1H NMR (CDC1₃, 400 MHz): δ 8.62 (s, 1H), 8.54 (s, 2H), 3.95 (s, 6H); ¹³C NMR (CDC1₃, 100 MHz); δ 164.76, 142.43, 132.16, 129.84, 93.40, 52.62.

Example 3: One pot Sequential Sonagashira coupling: Synthesis of Compound 3 tetramethyl 5,5 ' - (ethyne- 1 ,2-diyl)diisophthalate) :

To a magnetically stirred mixture of dimethyl-5-iodoisophthalate 2 (10 g, 31.21 mmol), PdCl₂(PPh₃)₂ (1.53 g, 2.18 mmol) and Cul (0.594 g, 3.12 mmol) in dry degassed THF (50.00 mL) TMSA (2.2 mL, 15.60 mmol) and dry triethylamine (17.5 mL, 124.8 mmol) were added under an inert atmosphere. The solution was stirred at room temperature for 3 h to form the first Sonagashira coupling product (one side aryl coupled TMSA) which was monitored by TLC, then TBAF (8.97 g, 34 mmol) 0.3 M in THF was added drop wise for 3 h and further the reaction mixture was stirred at room temperature for 12 h. After completion of the reaction, the mixture was diluted with ethyl acetate and filtered through celite. The filtrate was washed with water followed by brine. The combined organic layers were dried over anhydrous Na₂S0₄ and concentrated in vacuo to give pale brown solid which was further subjected to fractional crystallisation using DCM to afford expected product as block-shaped thick crystals in good yield. (8.7 g, 68%).

mp: 193-195 °C; TLC (ethyl acetate:pet ether, 20:80 v/v): R_f = 0.4; IR (KBr) cm^"1: 3082 , 2949, 1861,1730 (C=0), 1630 (Ar); 1H NMR (CDC1₃, 400 MHz): δ 8.63 (s, 2H), 8.36 (s, 4H), 3.97 (s, 12H); ¹³C NMR (CDC1₃, 100 MHz): δ 165.70, 136.84, 131.32, 130.82, 123.81, 89.32, 52.88; MALDI- MS (m/z): [M+K]⁺ calcd. for C₂2Hi₈0₈, 449.06; found, 449.2.

Example 4: Synthesis of compound 4 (dodeca ester of hexaphenyl benzene):

Compound 3 (2.5 g, 6.09 mmol) was dissolved in dry 1,4-dioxane (150 ml) under argon atmosphere and followed by dicobaltoctacarbonyl (0.208 g, 0.609 mmol). The resulting mixture was refluxed for 6 h. Then the reaction was stopped and solvent removed under vacuum. The obtained residue was dissolved in DCM and filtered through celite®, the filtrate was further evacuated to give compound 4 as a colorless solid (2.4 g, 96 %).

mp: 345-347 °C; TLC (ethyl acetate/pet ether, 70:30 v/v): R_f = 0.5; IR (KBr) cm^"1: 3440, 3076, 3002, 2907, 2844, 1732 (C=0), 1604 (Ar); 1H-NMR (400 MHz, CDCI3): δ 8.18 (t, 6H), 7.82 (d, 12H), 3.80 (s, 36H); ¹³C NMR (100 MHz, CDCI₃): δ 165.25, 139.79, 138.93, 135.73, 129.78, 128.99, 52.24; MALDI- MS (m/z): [M+Na]⁺, [M+K]⁺ calcd. for 0,₆Η₅₄0₂₄, 1253.29, 1269.26; found 1253, 1269.

Example 5: Synthesis of compound 5:

100 mg of compound 4 was suspended in a mixture of 2 ml dioxane and 30 ml dry methanolic-methylamine at room temperature. The mixture was heated to 80 °C in stainless steel covered teflon-lined autoclave and further the heating was maintained at the same temperature for 12 h. Then the reaction mixture was slowly cooled to room temperature to obtain compound 5 as colorless crystals with quantitative yield.

m.p >350 °C (decomposes). IR (Nujol) cm^"1: 3300, 3076, 2924, 2859, 1642 (C=0), 1584; 1H-NMR (400 MHz, DMSO-d₆): δ 8.16(q, 12H), 7.75(s, 6H), 7.68(s, 12H), 2.71(d, 36H); ¹³C NMR (100 MHz, DMSO-d₆): δ 165.58, 139.54, 138.94, 133.22, 131.63, 123.93, 26.28; MALDI- MS (m/z): [M+Na]⁺, [M+K]⁺ calcd. for C₆6H₆₆Ni₂Oi2, 1241.48, 1257.46; found 1241, 1257.

Example 6: Synthesis of compound 6:

100 mg of compound 4 was suspended in 35 ml dry methanolic ammonia. The mixture was heated to 80 °C in stainless steel covered teflon-lined autoclave and heating was maintained at the same temperature for 12 h. After completion of the reaction, the reaction mixture was slowly cooled to room temperature to afford compound 6 as colorless crystals with quantitative yield. Further suitable crystal was subjected for single crystal X-ray diffraction. Example 7: Synthesis of compound 7:

mp:>350 °C (decomposes); IR (KBr) cm^"1: 3431, 3183, 1665 (C=0), 1618, 1584; 1H-NMR (400 MHz, DMSO-d₆): δ 7.83 (s, 6H), 7.67(s, 24 H [12 H of Ar, 12 H of H₂]); ¹³C NMR (100 MHz, CDC1₃): δ 166.64, 139.34, 138.69, 132.87, 131.79, 124.29; MALDI- MS (m/z): [M+Na]⁺, [M+K]⁺ calcd. for C₅₄H₄₂Ni₂Oi₂, 1073.29, 1089.27; found 1073, 1089.

Example 8: Crystals growing methods used for preparation of inclusion crystals

Inclusion of guest molecules in HPB was done in two methods.

A. Heating to dissolve method:

To the borosilicate vial containing lOmg of the compound, suitable guest molecules either neat or as a solution (1-2 ml) was added. Then, the vial was capped and heated to dissolve the compound. Further, the vial was set aside to allow crystals to form, which usually occurs on a timescale of several minutes to days. Crystals were generally appeared after the solutions reached to room temperature.

B. Solvothermal method:

In this case, crystals were prepared under solvothermal conditions, in the course of the reaction, while converting compound 4 to 6. 100 mg of compound 4 was suspended in a mixture of interested guest molecules and 35 ml dry methanolic ammonia. The mixture was heated to 80 °C in stainless steel covered teflon-lined autoclave and heating was maintained at the same temperature for 12 h. After completion of the reaction, the reaction mixture was slowly cooled to room temperature to give inclusion crystals as colorless blocks.

Table 1. Summary of the inclusion complexes of HPB(COOMe)i₂

12 Salicylaldehyde

6 DCM, (+/) S tyreneoxide Method- A

(+/)Styreneoxide @HPB(COOMe (+/)Styreneoxide

)12

7 Toluene @ HPB (COOMe) 12 DCM, Toluene Toluene Method- A

8 Pyridine @ HPB(COOMe) 12 DCM, Pyridine Pyridine Method- A

9 Aniline@HPB(COOMe)12 DCM, Aniline Aniline Method- A

10 N- DCM, N- N-methylaniline Method- A methylaniline @ HPB (COOMe) 12 methylaniline

Table 2. Summary of the inclusion complexes of supramolecular sponge HPB(CONH₂)i₂

Table 3. Summary of the inclusion complexes of supramolecular sponge HPB(CONH. Me)i2

X-ray Crystallography: Single crystal structure of all Crystals were determined by measuring X-ray intensity data on a Bruker SMART APEX II single crystal X-ray CCD diffractometer having graphite-monochromatised (Μο-Κα = 0.71073 A) radiation (exception: H₂0@ HPB(CONHMe)i_2i data collected in Bruker APEX II Cu source). The X-ray generator was operated at 50 kV and 30 mA. A preliminary set of cell constants and an orientation matrix were calculated from total 36 frames. The optimized strategy used for data collection consisted different sets of φ and ω scans with 0.5° steps in φ/ω. Data were collected keeping the sample-to-detector distance fixed at 5.00 cm. The X-ray data acquisition was monitored by APEX2 program suit. All the data were corrected for Lorentz -polarization and absorption effects using SAINT and SADABS programs integrated in APEX2 package. The structures were solved by direct methods and refined by full matrix least squares, based on F, using SHELX-97. Molecular diagrams were generated using ORTEP-3 and Mercury programs. Geometrical calculations were performed using SHELXTL and PLATON.

Table 4. Crystallographic data for guest(s)@HPB(COOMe)i₂

Table 5. Crystallographic data for guest(s)@HPB(CONHMe)i₂

Table 6. Crystallographic data for guest(s)@HPB(CONH₂)i₂

Crystal MeOH.Dioxane. DMSO.MeOH.C₂H₅ MeOH.Urotropine. DMF.HBr® Parameters NH₃@ OH. NH_3, HPB(CONH₂)₁₂

HPB(CONH₂)i2 Hexane@ aminomethyleneimi

HPB(CONH₂)₁₂ ne.Cr®

HPB(CONH₂)i2

Growth MeOH, DMSO, MeOH, MeOH, NH_3i DCM DMF, H₂0, Solvents Dioxane,NH₃ C₂H₅OH, Benzylbromide, and Hexane, MeOH, or DMF, H₂0 additives NH₃ a-

Bromoisobutyr yl bromide

Crystal Tetragonal Monoclinic triclinic monoclinic system

Space P 4₃ 2i 2 P 2i/c P -l P 2i/n group

Z 4 2 2 4 a, A 15.5860(2) 15.9038(17) 15.7151(3) 14.0452(9) b, A³ 15.5860(2) 13.7217(16) 15.7851(4) 15.7454(10) c, A 30.0077(5) 17.5361(19) 21.2184(5) 20.3508(13) a, deg 90 90 70.6330(10) 90 β, deg 90 93.660(6) 81.8590(10) 102.861(3)

J, ^de 90 90 61.9360(10) 90

V, A³ 7289.57 3819.05 9838 4387.6(5)

Example 9: Supporting evidence for the presence of ammonia as a guest in the crystal of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂

a) pH paper test:

Crumbled crystals of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂ was taken in a glass vial on the top of that water dipped pH paper was kept and slowly warmed from room temperature to 70 °C. The pH paper color gradually turned into bluish green (Figure 10) suggesting the slow release of ammonia from the crystal lattice upon heating.

b) Thermogravimetric Analysis (TGA)

Thermogravimetric analysis (TGA) was conducted to determine the weight loss upon increasing temperature at a constant rate. The crystals of MeOH.dioxane.NH₃@ HPB(CONH₂)i₂ was removed from mother liquor and TGA was recorded. The weight loss of crystals showed 10% at below 250 °C corresponding to gradual loss of guest molecules such as ammonia, dioxane, methanol. The weight loss observed at above 350 °C due to the decomposition of the compound 6. The gradual weight loss of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂ (in the temperature range 30- 120° C ) is attributed to the loss of guest molecules from the crystal structure. The gradual weight loss due to slow escaping of guest molecules implies that the number of guest molecules interacted with the host molecules are temperature and time dependent.

The gradual weight loss is attributed to the instability of the crystals under ambient conditions and is therefore nearly 8% (at a temperature range 30- 120° C) since the guest molecules have gradually escaped upon preparing the sample for TGA analysis.

c) Infrared analysis (IR) IR spectrum of fresh samples shows umbrella mode (1015 cm^" ) absorption which is absent in the case of heated sample attributed to the presence of ammonia in the former and no/negligible amount of ammonia in the later. The relative broadening of the fresh sample possibly dynamic motion and escape of kinetically trapped ammonia and other guest molecules.

Example 10: Surface Characterization of MeOH.Dioxane.NH₃@HPB(CONH₂)i₂

In order to determine the morphology and porous nature of crumbled crystal of

MeOH.Dioxane.NH₃@HPB(CONH₂)i2 SEM was obtained,

a) Scanning electron microscope (SEM)

Crumbled crystal sample was analyzed on a FEI make SEM system of Quanta 200 3D series (dual beam ESEM) bearing tungsten filament as the electron source operated at 10 kV. The SEM image (Figure 11) shows clubbed scale-like particles in the surface of the solid, which seems while escaping of the low volatile guest molecules from the crystal and possibly crystal broken into small pieces of scale like units.

Advantages of the invention:

1. Provide twelve-armed hexaphenyl benzene (HPB)-based supramolecular sponges with very high thermal stability (TGA above 300° C).

2. m-substituted amides projected in two planes enhance the assembly and the formation of cavities.

3. Well standardized synthetic protocols and new methodologies are introduced to prepare the material in large scale.

4. Easily modifiable functional groups in a single step.

5. Single host molecule template can be used for including a variety of guest molecules.

Claims

WE CLAIM:

1. A twelve-armed hexaphenyl be -based supramolecular sponges of Formula (I).

Formula I

wherein R=OR\ Br, CI, F, NR'R", NHNH₂;

wherein R' and R" is independently selected from the group consisting of hydrogen, alkyl, aryl, carbocycle, aromatic or non-aromatic heterocycle, metal and peptide.

A composition comprising supramolecular sponge of Formula (I) as claimed in claim 1 and a guest molecule.

The composition as claimed in claim 2, wherein said sponge encapsulates guest molecules in voids of crystal lattice through co-operative interplay of multivalency, noncovalent forces and backbone rigidity.

The composition as claimed in claim 2, wherein said guest molecule is selected from group consisting of ammonia, DMSO, DMF, NMP, methanol, ethanol, hexane, HCOOH, [12]- crown-4 ether, Benzene, Salicylaldehyde, (+/)Styreneoxide, Toluene, Pyridine, Aniline and N-methylaniline.

A process for preparation of supramolecular sponge of Formula (I) as claimed in claim 1 , wherein said process comprising the steps of:

a) adding iodine to a stirred solution of sodium periodate in acid at the temperature ranging from 36°C to 40°C followed by stirring for the time period ranging from 30 to 45 mins; further adding dialkyl isophthalate and continuing the stirring for the time period ranging from 12 to 14 hours to obtain dialkyl-5-iodoisophthalate;

b) one pot sequential Sonagashira coupling comprising adding trimethylsilylacetylene (TMSA) and dry amine base to a stirred solution of dialkyl-5-iodoisophthalate as obtained in step a)_T palladium catalyst, copper cocatalyst in dry solvent under an inert atmosphere; stirring resulting mixture at the temperature ranging from 25°C to 30°C for the time period ranging from 3 to 4 hours to obtain Sonagashira coupling product (one side aryl coupled TMSA);

c) adding Tetra-n-butylammonium fluoride (TBAF) dropwise into said Sonagashira coupling product as obtained in step b) drop wise for 3 to 4h, further stirring reaction mixture at the temperature ranging from 25°C to 30°C for the time period ranging from 12 to 14 hours to obtain compound 3 (tetramethyl 5,5'-(ethyne-l,2-diyl)diisophthalate,

Formula 3

d) refluxing the reaction mixture of compound (3) as obtained in step c) and trimerisation catalyst in suitable solvent for the time period ranging from 6 to 7 hours to obtain compound 4 (dode

Formula 4 f) heating reaction mixture of compound 4 as obtained in step d) and amination agent in a suitable solvent at the temperature ranging from 80°C to 90°C for the time period ranging from 12 to 14 hours in steel bomb to afford compound of Formula (I).

6. The process as claimed in claim 5, wherein said acid of step (a) is selected from a group consisting of sulphuric acid (H₂SO₄) and Oleum.

7. The process as claimed in claim 5,, wherein dialkyl isophthalate of step (a) is selected from a group consisting of dimethyl isophthalate, and diethylisophthalate.

8. The process as claimed in claim 5, wherein said amine base of step (b) is selected from a group consisting of trimethylamine and diisopropylethylamine.

9. The process as claimed in claim 5, wherein palladium catalyst of step (b) is selected from a group consisting of Bis(triphenylphosphine)palladium(II) dichloride and Tetrakis(triphenylphosphine)palladium(0).

10. The process as claimed in claim 5, wherein said copper cocatalyst of step (b) is copper iodide (Cul).

11. The process as claimed in claim 5, wherein dry solvent of step (b) is selected from a group consisting of tetrahydrofuran (THF) and dioxane.

12. The process as claimed in claim 5, wherein said trimerisation catalyst of step (d) is selected from a group consisting of Dicobalt octacarbonyl and [PdCl₂(CH₃)₂].

13. The process as claimed in claim 5, wherein solvent of step (d) is selected from a group consisting of dioxane and toluene.

14. The process as claimed in claim 5, wherein said amination agent of step (e) is selected from a group consisting of methanolic methylamine, methanolic ammonia and hydrazine hydrate.

15. The process as claimed in claim 5, wherein solvent of step (e) is selected from a group consisting of dioxane, methanol and tetrahydrofuran.