WO2015132433A1 - Molecular nanocapsules for the selective separation of fullerenes - Google Patents

Abstract

The invention relates to molecular nanocapsules formed by self-assembly and based on tetracarboxlated (metallo)porphyrins and metal macrocyclic compounds, joined by M-carboxylate binding, and counter-ions, as well as to the use thereof for the selective separation and/or purification of fullerenes.

Description

 Molecular nanocapsules for selective separation of fulerenes

DESCRIPTION

The present invention relates to molecular nanocapsules formed by self-assembly and based on complexes and metalloporphyrins and their use for purification and / or selective separation of fulerenes.

STATE OF THE TECHNIQUE

The fulerenes are nanometric molecules (~ 1 nm in diameter) with applications in a wide range of fields from the science of materials to their use in drugs. Today, the derivatives of fulerene are the reference type n materials for the construction of organic photovoltaic devices. The search for molecular receptors for fulerenes, essentially for C60, began in the 90s to be able to have minimum quantities that allowed characterizing the properties of the material. From the point of view of molecular recognition, fulerenes are very peculiar host molecules. Its unusual shape (approximately spherical, maximizing the surface / volume ratio) and its chemical nature (non-polarized polyenes) restrict the types of non-covalent forces that can be used for their association with dispersion forces (π-π and van der Waals).

The separation and purification of fulerenes from mixtures with other allotropic forms of carbon is an unsolved problem. There is a great interest in overcoming the tedious and difficult chromatographic extractions that are currently used to separate the most common fulerenes purely. Among them, C60 and C70 are the best known and studied precisely because of their greater availability, although their cost remains high or very high due to the need for large amounts of solvents used in chromatographic purification processes. In addition, the separation and purification of larger bellows, larger than C70 (known as "higher fullerenes") is today the biggest problem for the study of its properties. For the separation and purification of "higher fullerenes" the classical chromatographic methods are unacceptable due to their low solubility and the many necessary chromatographic cycles, reasons for which the study of these compounds is clearly underdeveloped.

As an alternative to chromatographic extractions in recent years, two types of strategies have been used for encapsulation of fulerenes: a) the use of host molecules of a completely organic nature and with apolar groups (aromatic rings) of suitable dimensions for encapsulation of fulerenes , and b) the use of hosts containing transition metals.

In both approaches, the subsequent release of the host is achieved in several ways: a) acid-base treatment to achieve the opening of the capsule and the precipitation of the fulerene, b) the use of non-invasive external physical stimuli (irradiation with light) a room temperature and c) displacing the fulerene with a substrate with greater affinity towards the host.

There are selective host-host systems for C60, such as cyclodextrins or calix [8] arenes. In these systems the release of fulerene is difficult due to its high stability (Atwood, J.L .; Koutsantonis, G.A. and Raston, C. IL Nature, 368, 229 (1994)).

There are some exceptions, such as the calix [5] double sands developed by Fukazawa et al., Capable of extracting C94 and C96 from mixtures of fulerenes. These host-host systems treated at temperatures above 100 ° C allow the release of the aforementioned fulerenes due to a conformational change of the host. However, these hosts cannot be reused for the same application (Haino, T .; Fukunaga, C; Fukazawa, Y. Org. Lett., 8, 3545-3548 (2006)). On the other hand, the dimeric cyclic systems of Aida et al., Which contain two porphyrin units, are capable of extracting fulerenes greater than C76 from mixtures of fulerenes. Through the use of more selective hosts for these systems, such as 4,4'-bipyridine, the authors demonstrate the obtaining of mixtures enriched with "higher fullerens" (for example of mixtures C102-C1 10) and without a trace of the majority C60 and C70 (Shoji, Y .; Tashiro, K .; Aida, TJ Am. Chem. Soc, 126, 6570-6571 (2004)).

In addition, Mendoza et al. Has developed a supramolecular system based on cyclotriveratrylene receptors that contain three 4-ureidopyrimidinone (UPy) units and self-assemble using hydrogen bridge bonds. The authors have shown that this system is capable of encapsulating preferably C84 ahead of C70 and well ahead of C60 due to the different association constants. The release of the fulerenes is carried out by treatment with trifluoroacetic acid of solutions of the host-host system in THF (tetrahydrofuran), causing precipitation of the fulerenes in question. (Huerta, E .; Metselaar, GA; Fragoso, A .; Santos, E .; Bo, C. and de Mendoza, J. Angew. Chem. Int. Ed., 46, 202-205 (2007); Huerta, E .; Cequier, E. and de Mendoza, J. Chem. Commun., 5017-5018 (2007)). A similar strategy has been developed by Zhang et al. (Zhang, C; Wang, Q .; Long, H. and Zhang, W. J. Am. Chem. Soc, 133, 51 (201 1)).

Therefore, there is great interest in developing hosts capable of encapsulating and releasing selectively and differently controlled fulerenes of different sizes.

DESCRIPTION OF THE INVENTION

The present invention relates to the synthesis of molecular nanocapsules based on self-assembly by means of coordination chemistry of metal macrocyclic compounds with tetracarboxylated (metallo) porphyrins, and their use as sponges of fulerenes of different dimensions. The The nanocapsules obtained are tetragonal prismatic in nature with a large interior space capable of encapsulating a molecule of fulerene of different dimensions. The possibility of varying the design within the same family of nanocapsules makes it possible to have a technology to encapsulate and selectively release and will release fulerenes of a certain size.

The nanocapsules of the present invention have advantages in different aspects of the separation and purification of fulerenes. The use of a ligand with n = 2 provides the ability to absorb inside it from C60 to C84. The use of a ligand with n = 1 is expected to be effective for the absorption of small-size fulerenes (<C60), while ligands with n = 3 would be effective for the absorption of larger-sized fulerenes (> C84).

The nature of these nanocapsules is highly modular and in a simple way, the use of different metals in the porfihna is understood as an element that will allow and modify the affinity of the fulerenes for the capsules. Finally, the octacathonic nature of the nanocapsules and the use of different counterions constitute elements of system versatility that must allow the use of the capsules in different solvents.

Therefore, a first aspect of the present invention relates to a nanocapsule formed by two parallel tetracarboxylated (metallo) porphyrins of general formula (I) linked by four metal macrocyclic compounds of general formula (II) through an M-carboxylate bond , and counterions (X) in a suitable number to compensate for the octacathic charge of the nanocapsule.

(l) (II) where: Μ 'is selected from the list comprising 2H, Zn, Cu, FeCI, Ir, Pd, Pt, Ag, AuCI, Ni, Ru, Al, Pb, SnCI ₂ , InCI, SbCI, TiO, ZrCI ₂ , CrCI and VO; preferably IW is 2H, Zn, Cu, FeCI, Ir, Pt, Ag, AuCI, Ni, Ru, Al, Pb, SnCI ₂ , InCI, SbCI, TiO, ZrCI ₂ , CrCI and VO;

 M is a metal that is selected from the list comprising Pd, Cu, Pt, Ni and Zn;

each Ri and each R ₄ independently represent a hydrogen or a halogen;

each R ₂ and each R ₃ independently represent a hydrogen or a (C1-C7) alkyl group;

 n has a value of 1, 2 or 3.

By "halogens" is meant in the present invention a bromine, chlorine, iodine or fluorine atom. Preferably it is fluorine.

The term "alkyl" refers in the present invention to aliphatic, linear or branched chains, having 1 to 7 carbon atoms, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, t- butyl, s-butyl, n-pentyl, etc. Preferably it has 1 to 4 carbon atoms, more preferably methyl, ethyl, n-propyl, i-propyl or t-butyl and even more preferably it is methyl.

By "fulerene" is meant in the present invention a molecular form of carbon, with a number of carbons equal to or greater than 20 and which can be classified by the number of carbons in: small fulerenes, below C6o; standard bellows, which would be Cm and C70; and fulerenos large, greater than C ₇ o. As fulerenos we also refer to endofulerenes and functionalized fulerenes. Endofulerenes are fulerenes that contain encapsulated metal particles or other molecules, can have the following formula: M " _m @ C _n ; where M" is a particle, preferably La, Se, Ce, N, Sc ₃ N, Lu ₃ N, Gd ₃ N, C2SC4, m is the number of particles and can have a value between 1 and 5; and n is the carbon number of the fulerene, preferably it has the values 60 <n <84. On the other hand, the functionalized fulerenes can be for example, PCBM-C ₆ or ([6,6] -phenyl-C ₆ i-butyrate methyl) PCBM-C ₇₀ ([6,6] - methyl phenyl-C ₇ i-butyrate).

In a preferred embodiment, the counterion (X) of the nanocapsule is selected from CF3SO3 ^" , CF3CO2 ^" , CI ^" , Br, CI0 ₄ ^" , PF ₆ ^" , SbF ₆ ^" , BF ₄ ^" , N0 ₃ ^" , BPh ₄ ^" , S0 ^2" , P0 ₄ ^{3 "} or BARF ^" . More preferably X is CF3SO3 ^" , BARF ^" or any combination thereof; where Ph is phenyl and BARF ^" is [B [3,5- (CF ₃ ) 2C6H ₃ ] ₄ ] ^" . The number of counterions to be used will be adequate to compensate for the octacathionic charge of the nanocapsule, for example, in the case of being monoanionic, the total number of counterions to neutralize the nanocapsule is eight, four if they are dianionic, or any possible combination of same.

In another preferred embodiment, each R1 independently represents hydrogen or fluorine, preferably all R1 of the nanocapsule is hydrogen.

In another preferred embodiment, each R ₂ independently represents a hydrogen or an alkyl group (Ci-C ₄ ), even more preferably all R ₂ of the nanocapsule are methyl. In another preferred embodiment, each R ₃ independently represents a hydrogen or a (C1-C4) alkyl group, more preferably all R ₃ of the nanocapsule are methyl.

In another preferred embodiment, each R ₄ independently represents hydrogen or fluorine, preferably all R ₄ of the nanocapsule is hydrogen.

In another preferred embodiment, M is Pd or Cu and M 'is Zn or Pd.

In another preferred embodiment, R1 is hydrogen, R ₂ and R3 are methyl, R ₄ is hydrogen, M is Pd, IW is Zn, n is 2 and X is CF3SO3 ^" or BARF.

In another preferred embodiment, R1 is hydrogen, _R2 and R3 are methyl, _R4 is hydrogen, M is Cu, Pd IW, n is 2 and X is CF3SO3 ^".

Another aspect of the present invention relates to the use of the nanocapsule of the present invention, for the separation and / or purification of fulerenes.

When n is 2 in the metal macrocyclic compounds of general formula (II), the nanocapsule is useful for the separation and / or purification of fulerenes of size between C60 and C84, both included. When n is 1 in the metal macrocyclic compounds of general formula (II), the nanocapsule is useful for the separation and / or purification of fulerenes of a size smaller than C60. And when n is 3 in the metal macrocyclic compounds of general formula (II), the nanocapsule is useful for the separation and / or purification of fulerenes of a size greater than C84.

Another aspect of the present invention relates to the possibility of encapsulating the various liquid phase fulerenes (mixture of solvents where nanocapsule and fulerenes are dissolved), or alternatively with one of the solid phase components. For example, nanocapsule suspension (solid state) in solution of fulerenes in, for example, toluene, or suspension of fulerenes (solid state) in nanocapsule solution in, for example, acetonitrile.

 The present invention demonstrates the ability of nanocapsules to encapsulate fulerenes of different sizes. It has been demonstrated by high-resolution mass spectrometry and, in some cases, by X-ray crystallography the encapsulation of C60, C70, C76, C78, C84 from mixtures of sooty soles ("Fullerene extract": purchased at SES Research, with a C60 content of 70%, C70 of 28%, higher fullerenes of 2%. "Fullerene soot": Aldrich, C60 is 5.32%, that of C70 is 1.54%, and that of higher fullerens ( > C70) less than 0.14%)

Therefore, another aspect of the present invention relates to a method of encapsulation of rubber bellows of size between C60 and C84, both included, comprising the following steps:

to. dissolve a nanocapsule formed by two parallel tetracarboxylated (metallo) porphyrins of general formula (I) joined by four metal macrocyclic compounds of general formula (II) through an M-carboxylate bond, and counterions (x) in a suitable number to compensate The octacathic charge of the nanocapsule:

where: M 'is selected from the list comprising 2H, Zn, Pd, Cu, FeCI, Ir, Pt, Ag, AuCI, Ni, Ru, Al, Pb, SnCI ₂ , InCI, SbCI, TiO, ZrCI ₂ , CrCI , VO;

M, Ri, R ₂ , R3 and R ₄ are defined above and n is 2;

 with a solvent selected from acetonitrile, CH2CI2, acetone, methanol or any combination thereof;

b. add the dissolved nanocapsules from step (a) or the undissolved nanocapsules, leaving the nanocapsules in suspension, to the fulerenes dissolved in toluene, 1,2-dichlorobenzene, carbon disulfide or any combination thereof; or

b '. alternatively to step (b) add to the dissolved nanocapsules in step (a) the solid-state, undissolved, the fulerenes, with said fulerenes being suspended;

where the proportion of the solvent of the fulerene of step (b) / solvent of the nanocapsule of step (a) is between 9/1 to 4/1 and the temperature at which the above steps are carried out is between 0 ° C and 50 ° C, preferably the temperature is 20-30 ° C, and more preferably 25 ° C. In a preferred embodiment of the encapsulation method, the dissolved nanocapsules of step (a) are added to the dissolved fulerenes, that is to say in a liquid state.

In another preferred embodiment, the rubber steels to be encapsulated are selected from C60, C70, C76, C78, C84 or any of their mixtures.

In a more preferred embodiment the proportion of the solvent of the fulerene of step (b) / nanocapsule solvent of step (a) is 4/1. More preferably the solvent of step (a) is acetonitrile, and / or the solvent of step (b) is toluene.

In a preferred embodiment of the encapsulation method of the present invention, M 'is Zn, M is Pd, Ri and R ₄ are H, R ₂ and R 3 are methyl and X is BARF ^" of the nanocapsule of step (a).

In another preferred embodiment of the encapsulation method of the present invention, I is Pd, M is Cu, R1 and R ₄ are H, R ₂ and R 3 are methyl and X is CF 3 SO 3 ^" of the nanocapsule of step (a).

After the encapsulation, and secondly, the extraction of the encapsulated fulerenes is carried out exclusively with solid-state host-host system washes with different solvents, whereby the frelerenes released are obtained directly in solution while the remaining solid residue It consists mostly of empty nanocapsule, which is prepared without any additional operation for another encapsulation cycle. The recycling process has been shown to be effective using an encapsulated C60 sample, and has been tested up to 5 times so that the integrity of the nanocapsule is not affected.

Therefore, another aspect of the present invention relates to the controlled release of encapsulated fulerenes. A preferred embodiment relates to a method for the separation of C60 from a mixture of fulerenes, comprising:

 to. encapsulating said fulerenes by the encapsulation method of the invention described above; Y

 b. wash three times (preferably a minimum of approximately 0.3 ml_ per wash) the encapsulated fulerenes of step (a) with a mixture of 1,2-dichlorobenzene: CS2 in a ratio of 1: 1 to 0: 1 and where Encapsulated fulerenes are supported on a filtration column (preferably celite ®).

In another preferred embodiment with mixtures of C60 and C70, selective release with washing of the host-host compound in solid phase with organic solvents of different polarity can be performed.

More preferably, a method for the selective and sequential separation of C60 and C70 from a mixture of rubber bellows comprises separating the fulerene of size C60 by steps (a) and (b) of the method described above, in this way C60 (dissolved) is completely released. in the solvent mixture) while C70 remains encapsulated and in a solid state; and c. The precipitate obtained in step (b) is suspended in toluene and treated with triflic acid. The C70 dissolves in the medium and recovers completely and the remaining solid can be treated for the recovery of the nanocapsules and their reuse.

Another aspect of the present invention relates to the recycling of the nanocapsule, since once the washes have been carried out for the extraction of the encapsulated fulerene, the nanocapsule can be reused after at least 5 cycles of extraction by washing.

Therefore, the above-described methods of encapsulation and separation of C60 and, optionally of C70, may comprise an additional step in which the solid comprising the nanocapsule and fulerene is dried and NEt ₃ is added. (Et is ethyl) and subsequently dissolved with CH ₃ CN, and thus the nanocapsule is recovered for later use.

Therefore, it has been shown that the nanocapsule family of the present invention has a very high affinity for encapsulation of fulerenes and that a methodology for selective extraction has been developed with the possibility of reusing the nanocapsule for additional extraction cycles.

Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1: Graphical representation of the nanocapsules of the invention, (a) represents the compound of general formula (I) (3) and the compound of general formula (II) (2) without the metals M; (b) represents the synthesis of two compounds of general formula (I) (3) with four compounds of general formula (I) (1-2), to form the nanocapsule (4); (c) represents a structural scheme of a nanocapsule where n is 2.

Fig. 2: High-resolution ESI-MS mass spectrometry analysis of the precipitate obtained after five cycles of extraction of the C60 from C6o @ 5- sample (BARF) ₈ by washing with 1,2-dichlorobenzene: CS2 (1: one ).

Fig. 3: ESI-MS of the mixture formed after adding fullerene soot to nanocapsule 5- (BARF) ₈ Fig. 4: Analysis by ESI-MS showing the highest affinity of C70 with respect to C60 (10 times higher).

Fig. 5: Differentiated separation of fulerenes according to the excess of "fullerene extract" with respect to capsule 5- (BARF) ₈ . Enrichment of C84 using large excesses of "fullerene extract".

EXAMPLES

Example 1: Synthesis of the nanocáosulas of the invention

Synthesis of the Me2pp ligand (and its syntheses S2pp and H2pp) S2pp: 1.2 g of biphenyl 4,4'-medicarbaldehyde (0.48 mmol) are dissolved in 200 ml of THF. Another solution of 0.51 g of diethylenetriamine (0.49 mmol) in 100 ml of THF is prepared. Using a compensated addition funnel, the dialdehyde solution is added dropwise to the diethylenetriamine solution. The mixture was stirred for 10 h. The formation of a white powder is observed, and the solid is filtered off. (Yield: 64.6%). ¹ H-NMR (400 MHz, CDCI ₃ ) δ ppm: 8.31 (s, 4H, N = CH), 7.56-7.54 (d, J = 8.32 Hz, 8H, arom), 7 , 41 -7.38 (d, J = 8.32 Hz, 8H, arom), 3.80-3.78 (m, 8H, CH ₂ ), 3.00-2.98 (m, 8H, CH ₂ ), 2, 14 (s, 2H, NH). FT-IR v (cm ^"1 ): 1372 (CN st), 1643 (C = N st), 1650-2000, 2879, 2945 (CH st, sp ² ), 3027 (= CH st), 3062 (arC- H st), 3300 (NH st) ESI-MS (m / z): 555.3 ({S2pp + (H ⁺ )}), 281, 7 ({S2pp + (H ⁺ ) ₂ ).

H2pp: 0.55 g of S2pp (0.99 mmol) was added to a 250 ml flask and dissolved with 50 absolute ethanol. Then 0.237 g of NaBH ₄ (13.22 mmol) are added slowly. The reaction mixture was stirred for 16 h, 5 ml of 1 M HCI was added, and the solution was stirred an additional 45 minutes. After this time, the ethanol was removed under reduced pressure, and 20 ml of water is added to the reaction mixture. The H2pp product, which remains in the aqueous phase, is extracted with CH ₃ CI (3x25 ml). The organic phases are mixed, dried with anhydrous MgSO4 and filtered. Finally the solution is dried under vacuum pressure. The product was obtained as a white solid. (Yield: 78, 1%). ¹ H-NMR (400 MHz, CDCI ₃ ) δ ppm: 7.48-7.46 (d, J = 8.24 Hz, 8H, arom), 7.36-7.34 (d, J = 8, 20 Hz, 8H, arom), 3.8 (s, 8H, CH ₂ ), 2.90-2.82 (m, 16H, CH ₂ ), 1, 68 (broad band, NH). FT-IR v (cm ^"1 ): 1 103 (CN st), 1496, 1437 (CH ₂ δ), 1650-2000, 2876, 2922 (CH st, sp ² ), 3294 (NH st).

Me2pp: 0.66 g of H2pp (1.2 mmol) was added to a 100 ml flask and mixed with 10 ml of formaldehyde, 8 ml of formic acid and 10 ml of water. The resulting mixture is heated at reflux for 12 h. After this time, the reaction mixture was cooled to room temperature and the solvent was removed under reduced pressure. Then 25 ml of 30% NaOH are added. The product was extracted with CHCI3 (3x25 ml). The organic phases were combined, dried with anhydrous MgSO4 and filtered. The remaining solution is dried under vacuum pressure, and the product obtained is purified by recrystallization with acetone. (Yield: 39.6%). ¹ H-NMR (400 MHz, CDCI ₃ ) δ ppm: 7.39 (d, J = 8.24 Hz, 8H, arom), 7.29 (d, J = 8.24 Hz, 8H, arom), 3.47 (d, J = 20.06 Hz, 8H, CH ₂ ), 2.57-2.49 (m, 16H, CH ₂ ), 2.28 (s, 6H, CH ₃ ), 2.22 ((s, 12H, CH ₃ ). FT-IR v (cm ^"1 ): 1462 (CN st), 1650-2000, 2780 (CH st, sp ³ ), 2935 (arC-H st), 2967 (C - H st, sp ² ) ESI-MS (m / z): 647.4 ({Me2pp + H} ⁺ ).

Molecular Clip (Pd-1) (FRAGMENT 1 -2 of Fig. 1 with M = Pd). Pd-1 ^» (AcO) 4 (where AcO is acetate) In a round bottom flask of 0.03 g of Me2pp ligand (0.05 mmol), 0.021 g of Pd (AcO) ₂ (0.1 mmol) and 10 ml of anhydrous CH ₃ CN were mixed. The mixture is heated at reflux temperature, under nitrogen atmosphere, for 18 h. The solvent of the solution obtained is concentrated to a volume of 2 ml, under reduced pressure, filtered through Celite® and recrystallized by slow diffusion of diethyl ether. [Pd ₂ (Me2pp) (AcO) 2] (AcO) 2 is obtained as a yellow crystalline solid. (Yield: 81.7%). ¹ H-NMR (400 MHz, CD ₃ CN) δ ppm: 8.37 (d, J = 8 Hz, 9.3 H, arom), 8.15 (d, J = 8 Hz, 8 H, arom), 7.94 (d, J = 8 Hz, 1 .3 H, arom), 4.06 (d, J = 13 Hz, 5.1 H, -CH ₂ -), 3.68 (m, 4.8 H, -CH ₂ -), 3.34 (s, 12 H, N-CH ₃ ), 3.31 (s, 2.2 H, N-CH ₃ ), 3.25 (m, 4.8 H, -CH ₂ -), 3.1 1 (d, J = 13 Hz, 4.8 H, -CH ₂ -) , 2.38 (d, J = 14 Hz, 4.7 H, -CH ₂ -), 2.30 (d, 4.8H, -CH ₂ -), 2.07 (s, 6 H, AcO), 2.05 (s, 0.9H, AcO ), 1.70 (s, 7.2 H, AcO), 1.50 (s, 0.9 H, N-CH3), 1.41 (S, 6 H, N-CH ₃ ). ESI-MS (m / z): 1307.3 ({[Pd ₂ (Me2pp) (AcO) ₂ ] (AcO) i} ^{1 +} ), 489.1 ({[Pd ₂ (Me2pp) (AcO) ₂ ]} ²⁺ ) .

Pd-1 (AcO) ₂ (CF ₃ SO ₃ ) ₂ : Pd-1 (AcO) ₂ (CF ₃ SO ₃ ) ₂ is obtained from Pd-1 ^» (AcO). 0.04 g of Pd-1 ^» (AcO) (0.04 mmol) was dissolved in 25 ml of CH ₃ CN. An excess of NaCF ₃ S0 ₃ (1 to 4.2 equivalents) is added and the mixture is stirred vigorously for 6 h. The reaction mixture was concentrated to a volume of 2-3 ml under reduced pressure, filtered through Celite® and recrystallized by slow diffusion of diethyl ether. A yellow crystalline solid is obtained. (Yield: 90, 1%).

Molecular Clip (Cu-1) (FRAGMENT 1 -2 of Fig. 1 with M = Cu). Cu-1 (CF ₃ SO ₃ ) ₄ : to a suspension of Me2pp ligand in CH ₃ CN (40 mg, 0.06 mmol, 1.5 mL), a solution of Cu (CF ₃ SO ₃ ) 2 was added in CH ₃ CN (45.0 mg, 0.12 mmol, 1 mL). After stirring 30 minutes, the solution was filtered through Celite® and recrystallized by diffusion of diethyl ether. A dark red crystalline solid was obtained (yield: 94.7%) ESI-MS (m / z): 1221 .2 ({(Cu-1) (CF ₃ SO ₃ ) ₆ } ^{1 +} ), 535.0 ({(Cu-1) (CF ₃ SO ₃ ) ₅ } ²⁺ ), 307.7 ({(Cu-1) (CF ₃ SO ₃ ) ₄ } ³⁺ ).

Synthesis of molecular nanocapsule 4 ^» (CF ₃ S0 ₃ ) 8 (Fig 1, where M = Cu and M '= Pd, consisting of two (metallo) porphillins of formula (I) where all R ₄ are hydrogen and M 'is Pd linked to four macrocycles of formula (II) (Cu-1 above) through M-carboxylate bonds and eight CF3SO3 counterions)

To a suspension of 5, 10, 15,20-tetrakis (4-carboxyphenyl) -porphyrin-Pd "in DMF (6.53 mg, 0.029 mmol, 1 ml_) was added a solution of triethylamine in DMF (4 μΙ_ in 0 , 5 ml_) Simultaneously, molecular clip Cu-1 was dissolved in DMF (20 mg, 0.014 mmol, 1.5 ml_) and added dropwise to the metalloporphyrin solution After stirring overnight the solution was filtered through Celite® and ether was recrystallized by diffusion, a dark red crystalline solid was obtained (yield: 62.9%).

ESI-MS (m / z): 2886.4 ({4- (CF ₃ S0 ₃ ) ₆ } ²⁺ ), 1875.9 ({4 (CF ₃ S0 ₃ ) ₅ } ³⁺ ), 1368.4 ({4 (CF ₃ S0 ₃ ) ₄ } ⁺ ), 1064.8 ({4 (CF ₃ S0 ₃ ) ₃ } ⁵⁺ ), 862.9 ({4 (CF ₃ S0 ₃ ) ₂ } ⁶⁺ ), 718.3 ({4 (CF ₃ S0 ₃ )} ⁷⁺ ), 609.9 ({4} ⁸⁺ ).

Synthesis of molecular capsule 5- (CF ₃ S0 ₃ ) 8. (Fig. 1 nanocapsule where M = Pd and M '= Zn, consisting of two (metallo) porphillins of formula (I) where all R ₄ are hydrogen and M' is Zn joined by four macrocycles of formula (II) ( Pd-1 above) and eight CF ₃ S0 ₃ counterions)

5 (CF ₃ S0 ₃ ) ₈ : 10.56 mg of 5, 10, 15,20-tetrakis (4-carboxyphenyl) -porphyrin-Zn "(2, 0.01 mmol) were weighed into a 10 ml flask, then add 1 ml of DMF _¬. 10 μΙ of triethylenetetramine dissolved in 0.5 ml of DMF are added to the metalloporphyrin solution. Finally 30 mg of Pd-1 ^» (AcO) 2 (CF ₃ S0 ₃ ) 2 (0.02 mmol) complex dissolved in 2.5 ml of DMF are added to the mixture. The solution obtained is heated at 105 ° C under reflux for 16 h. After the reaction time, the mixture was cooled to room temperature, filtered through Celite® and recrystallized by diffusion of diethyl ether. (Yield: 67, 1%). ¹ H-NMR (400 MHz, CD ₃ CN) δ ppm: 8.60 (dd, 8 H, arom-porph), 8.58 (s, 16H, pyrrole ring), 8.35 (dd, J = 8 Hz, 8H, arom- porph), 8.30 (d, J = 8.5 Hz, 32

H, arom-clip), 8.15 (d, J = 8.5 Hz, 32 H, arom-clip), 8.10 (dd, J = 8 Hz, 8H, arom-porph), 7.98 (dd, J = 8 Hz, 8H , arom-porph), 4.07 (d, J = 13 Hz, 16 H, -CH ₂ -), 3.70 (m, 16H, -CH ₂ -), 3.60 (s, 48 H, N-CH ₃ ), 3.38 (m, 16 H, -CH ₂ -), 3.15 (d, J = 13 Hz, 16 H, -CH ₂ -), 2.49 (dd, J = 13.5, 16 H, -CH ₂ -), 2.39 (dd , J = 13.5, 16 H, -CH ₂ -),

I .58 (s, 24 H, N-CH ₃ ). ESI-MS (m / z): 1433.5 ({5 - ((CF ₃ S0 ₃ ) ₃ )} ⁺ ), 1 1 17.3 ({5 (CF ₃ S0 ₃ ) ₃ } ⁵⁺ ), 906.7 ({5 ( CF ₃ S0 ₃ ) ₂ } ⁶⁺ ), 755.5 ({5 (CF ₃ S0 ₃ )} ⁷⁺ ), 642.2 ({3 (CF ₃ S0 ₃ )} ⁸⁺ ).

Synthesis of molecular capsule 5- (BARF) ₈ . (Fig. 1 nanocapsule where M = Pd and M '= Zn, consisting of two (metallo) porphillins of formula (I) where all R ₄ are hydrogen and M' is Zn joined by four macrocycles of formula (II) ( Pd-1 above) and eight BARF counterions ^" )

5 (BARF) ₈ : 0.02 g of 5 ^» (CF ₃ S0 ₃ ) ₈ (3.2 μηποΐβε) dissolve in 10 ml of CH2CI2. An excess of NaBArF salt (1 to 10 equivalents) is added and the mixture is stirred vigorously for 16 h. The reaction mixture is filtered and the product is obtained by precipitation with diethyl ether. The purple powder was washed several times with diethyl ether to remove excess NaBArF. (Yield: 38%). ¹ H-NMR (400 MHz, CD ₃ CN) δ ppm: 8.60 (dd, 8 H, arom-porph), 8.58 (s, 16H, pyrrole ring), 8.35 (dd, J = 8 Hz, 8H, arom- porph), 8.30 (d, J = 8.5 Hz, 32 H, arom-clip), 8.15 (d, J = 8.5 Hz, 32 H, arom-clip), 8.10 (dd, J = 8 Hz, 8H, arom- porph), 7.98 (dd, J = 8 Hz, 8H, arom-porph), 7.68 (m, 96 H, NaBARF), 4.07 (d, J = 13 Hz, 16 H, -CH ₂ -), 3.70 (m , 16H, -CH ₂ -), 3.60 (s, 48 H, N-CH ₃ ), 3.38 (m, 16 H, -CH ₂ -), 3.15 (d, J = 13 Hz, 16 H, -CH ₂ -), 2.49 (dd, J = 13.5, 16 H, -CH ₂ -), 2.39 (dd, J = 13.5, 16 H, -CH ₂ -), 1.58 (s, 24 H, N-CH ₃ ). ESI-MS (m / z): 2147.99 ({5- (BARF) ₄ } ⁴ ), 1545.74 ({5 (BARF) ₃ }), 1 144.24 ({5 (BARF) ₂ } ⁶⁺ ), 857.48 ({ 5 (BARF)} ⁷⁺ ), 642.42 ({5 (BARF)} ⁸⁺ ).

The characterization of the hostless nanocapsules was performed by high resolution mass spectrometry (HR-ESI-MS), by X-ray diffraction and by NMR studies and infrared FT-IR spectroscopy.

Example 2: Encapsulation and Release of Fulerenes using nanocapsules

The prismatic tetragonal nanocapsule (5- (BARF) ₈ ) is capable of encapsulating leaflets of different sizes, mainly CQO, C ₇ O, C ₇ 6, C ₇ 8 and C8 ₄ . The encapsulation is carried out by mixing the box dissolved in acetonitrile and equimolar amounts of fulerenes dissolved in toluene (25 ° C, acetonitrile: toluene 1: 4). Alternatively, encapsulation is also effective by suspending 5- (BARF) ₈ in a solid state within a tollene solution in toluene, or by suspending fullerene in a solution of 5- (BARF) ₈ in acetonitrile. In addition, these fulerenes can be released from inside the nanocavity by washing with different organic solvents. This extraction is quick and simple, and is based on the difference in solubility of the fulerenes and the nanocapsule. By washing the nanobox with a solvent in which the fulerenes are highly soluble but the nanocapsule is not, we get it to remain in suspension and only solubilize the fulerenes. The solution containing the fulerenes is separated by filtration of the solid and finally the extracted fulerenes are precipitated by the addition of acetonitrile, and separated by centrifugation.

Preparation of C6o @ 5- (BARF) ₈ . 2.5 mg of nanocapsule 5 (BARF) ₈ (0.2 μίτιοΐβε, 1 equiv.) Was dissolved in 100 μΙ of CH ₃ CN. Then 1 equiv. of C6o was added together with 400 μΙ of toluene. The mixture was stirred at room temperature for 5 minutes. After the reaction time, the mixture is filtered through cotton and recrystallized by diffusion of diethyl ether. ¹ H-NMR (400 MHz, CD ₃ CN) δ ppm: 8.64 (dd, 8 H, arom-porph), 8.55 (s, 16H, ring pyrrole), 8.35 (dd, J = 8 Hz, 8H, arom-porph), 8.30 (d, J = 8.5 Hz, 32 H, arom-clip),

8.14 (d, J = 8.5 Hz, 32 H, arom-clip), 8.04 (dd, J = 8 Hz, 8H, arom-porph), 7.99 (dd, J = 8 Hz, 8H, arom-porph), 7.68 (m, 96 H, NaBARF), 4.07 (d, J = 13 Hz, 16 H, -CH ₂ -), 3.70 (m, 16H, -CH ₂ -), 3.60 (s, 48 H, N-CH ₃ ), 3.38 (m, 16 H, -CH ₂ -),

3.15 (d, J = 13 Hz, 16 H, -CH ₂ -), 2.49 (dd, J = 13.5, 16 H, -CH ₂ -), 2.39 (dd, J = 13.5, 16 H, -CH ₂ - ), 1.58 (s, 24 H, N-CH ₃ ). ESI-MS (m / z): 2328.14 ({C ₆ or @ 5- (BARF) ₄ } ⁺ ), 1689.89 ({C ₆₀ @ 5 (BARF) ₃ } ⁵⁺ ), 1264.40 ({C ₆ or @ 5 (BARF) ₂ } ⁶⁺ ), 960.48 ({C ₆₀ @ 5 (BARF)} ⁷⁺ ), 732.54 ({C ₆₀ @ 5 (BARF)} ⁸⁺ ).

Preparation of C ₇₀ @ 5 (BARF) ₈ . 2.5 mg of nanocapsule 5 (BARF) ₈ (0.2 μίτιοΐβε, 1 equiv.) Was dissolved in 100 μΙ of CH ₃ CN. Then 1 equiv. of C o was added together with 400 μΙ of toluene. The mixture was stirred at room temperature for 5 minutes. After the reaction time, the mixture is filtered through cotton and recrystallized by diffusion of diethyl ether. ¹ H-NMR (400 MHz, CD ₃ CN) δ ppm: 8.66 (dd, 8 H, arom-porph), 8.48 (s, 16H, pyrrole ring), 8.33 (d, J = 8.5 Hz, 32 H, arom -clip), 8.14 (d, J = 8.5 Hz, 32 H, arom-clip), 8.00 (m, 8H, arom-porph), 7.68 (m, 96 H, NaBARF), 4.07 (d, J = 13 Hz , 16 H, - CH ₂ -), 3.70 (m, 16H, -CH ₂ -), 3.60 (s, 48 H, N-CH ₃ ), 3.38 (m, 16 H, -CH ₂ -), 3.15 ( d, J = 13 Hz, 16 H, -CH ₂ -), 2.49 (dd, J = 13.5, 16 H, -CH ₂ -), 2.39 (dd, J = 13.5, 16 H, -CH ₂ -), 1.58 (s, 24 H, N-CH ₃ ). ESI-MS (m / z): 2358.19 ({C ₇₀ @ 5- (BARF) ₄ } ⁺ ), 1713.97 ({C ₇₀ @ 5 (BARF) ₃ } ⁵⁺ ), 1284.42 ({C ₇₀ @ 5 (BARF ) ₂ } ⁶⁺ ), 977.62 ({C ₇₀ @ 5 (BARF)} ⁷⁺ ), 747.53 ({C ₇₀ @ 5 (BARF)} ⁸⁺ ).

The release of the C60 fulerene from the inside of the nanocapsule from a pure sample of the C60-nanocapsule complex is performed by loading the sample (10 mg) of C6o @ 5- (BARF) ₈ in a solid state on a column using Celite® as a solid filter support. . Three consecutive 1 mL washes of the mixture 1, 2- dichlorobenzene / CS2 (1: 1) completely release the C60 from inside the capsule, leaving all the C60 in the filtrate and the empty capsule in solid state 5- (BARF) ₈ loaded in the column. Analysis of the solid sample remaining in the column by HRMS certifies that it consists of an empty box in a purity> 95%. Then the 5- (BARF) ₈ capsule loaded in the column is redissolved in CH3CN and recharged with C60 dissolved in toluene (CH3CN / 1/4 toluene mixture). Once loaded with C60, compound C60 @ 5- (BARF) ₈ is precipitated with diethyl ether and reloaded on the same chromatography column (celite® as solid support) used for the first wash. The same procedure is repeated up to 5 times and the integrity of 5- (BARF) ₈ is certified by HRMS after each wash. At the end of the 5 cycles, more than 54% of 5- (BARF) ₈ is recovered. The cash losses observed are mainly due to the dissolution process of 5- (BARF) ₈ after emptying of C60 and precipitation of C60 @ 5- (BARF) ₈ with diethyl ether, and not the decomposition of the compound. It is shown that the box works like a recyclable C60 sponge. (Fig. 2)

The nanocapsule 5- (BARF) ₈ is capable of encapsulating the different fulerenes present in the soot resulting from the production of fulerenes (fullerene extract), from C60 to C84. The encapsulation of fulerenes has been tested with "fullerene extract" (purchased from SES Research, with a content of C60 70%, C70 28%, large fulerene (higher fullerenes) 2%). Using a ratio of 1: 3 by weight of nanocapsule 5- (BARF) ₈ and commercial "fullerene soot" (Aldrich) (C60 is 5.32%, that of C70 is 1.54%, and that of "higher fullerenes" ( > C70) less than 0.14%, the remainder being amorphous carbon, carbon nanotubes and graphite, for which the nanocapsule is totally ineffective), it is capable of encapsulating C60, C70, C74, C76 and C84 exclusively, as is determined by high resolution mass spectrometry. (Fig. 3)

Encapsulation of the fulerenes at room temperature is quantitative (1: 1 stoichiometry) in seconds and at room temperature. Its encapsulation has been verified by high resolution mass spectrometry, by NMR studies (the nanocapsule and its adduct with the encapsulated fulerene are diamagnetic) and FT-IR spectroscopy. The encapsulation of C60 and C70 has also been contrasted by preliminary X-ray studies with synchrotron light. The higher proportion of C70 than of encapsulated C60 when its concentration is 4 times lower, clearly suggests a higher affinity for C70. The same reasoning can be done in relation to C84, C76 and C72, since their percentages are extremely small in the "fullerene extract" and yet they are clearly seen as encapsulated in Fig. 3 It has been determined by HRMS that the affinity of C70 is 10 times higher than that of C60 (Fig 4).

 If it has not been possible to calculate due to the lack of availability of pure sample of C72, C76 and C84, it is reasoned that these fulerenes have even greater affinity than the C70.

This allows us a differentiated separation of fulerenes depending on the excess of "fullerene extract" with respect to the capsule 5- (BARF) ₈ . Thus, it is clearly observed that when the ratio 5- (BARF) ₈ : "fullerene extract" in weight is 1: 3, basically C60 and C70 are encapsulated, while with very large excesses (1/300 ratios), very little is encapsulated amount of C60 in relation to C70, and it is also observed that clearly the C70 / C84 ratio decreases, indicating an enrichment of C84 as a fulerene with greater affinity (Fig. 5).

The release of the encapsulated fulerene mixture (in the experiment where the ratio 5- (BARF) ₈ : "fullerene extract" by weight is 1: 3) is performed as follows: 5 mg of the nanocapsule with fulerenes, fulerenes @ 5- (BARF) ₈ , is loaded in a solid state on a column with celite® as a solid support, and 3 washes of 1 mL of the mixture 1, 2-dichlorobenzene: CS2 1: 1 are performed, allowing the C60 to be released exclusively in a pure way, leaving on the column the solid residue consisting of empty capsule 5- (BARF) ₈ and capsule with equal or greater than C70 fulerenes. Later washed with CS2 exclusively allow to extract up to 10% of the C70 encapsulated in a pure way.

The release of the rest of higher fullerenes can be done in two ways: a) the use of excess triflic acid (CF3SO3H, 20 equivalents with respect to the capsule) added on a suspension of fulerenes @ 5- (BARF) ₈ (where the C60 has been previously released) at room temperature leads to irreversible disassembly of the nanocapsule and immediate release of the fulerene mix; b) the use of 3 equivalents of CF3SO3H allows to extract the fulerenos equal or larger than C70, due to a destabilization of the capsule without disassembling it. The addition of 3 eq of NEt ₃ (triethylamine) as a base to neutralize the triflic acid used is essential to recover the capsule completely (HRMS certified).

These tests demonstrate that the developed nanocapsule is capable of modeling the dimension of its interior space to accommodate guests of different sizes (from C60 to C84), thanks to the torsion capacity at the level of the eight metal-carboxylate coordination bonds and the slight flexibility inherent in the porphyrinic substructure.

Claims

CLAIMS Nanocapsule formed by two parallel (metal) tetracarboxylated porphyrins of general formula (I) linked by four metal macrocyclic compounds of general formula (II) through an M-carboxylate bond, and counterions (X):

where: M 'is selected from the list comprising 2H, Zn, Pd, Cu, FeCI, Ir,

Pt, Ag, AuCI, Ni, Ru, Al, Pb, SnCI ₂ , InCI, SbCI, TiO, ZrCI ₂ , CrCI, VO;

 M is a metal that is selected from the list comprising Pd, Cu, Pt, Ni and

Zn;

each Ri and each R ₄ independently represent a hydrogen or a halogen;

each R ₂ and each R ₃ independently represent a hydrogen or a (C1-C7) alkyl group;

n has a value between 1 and 3.

2. Nanocapsule according to claim 1, wherein M 'can be selected from the list comprising 2H, Zn, Cu, FeCI, Ir, Pt, Ag, AuCI, Ni, Ru, Al, Pb, SnCI ₂ , InCI, SbCI, TiO, ZrCI ₂ , CrCI, VO.

3. Nanocapsule according to any one of claims 1 or 2, wherein n is 2 or 3.

4. Nanocapsule according to any one of claims 1 to 3, wherein X is selected from CF ₃ SO ₃ ^" , CF ₃ CO ₂ ^" , CI ^" , Br ^" , CIO ^" , PF ₆ ^" , SbF ₆ ^" , BF ^" , NO ₃ ^" , BPh ₄ ^" , SO ^{2 "} , PO ^3" or BARF ^" .

5. Nanocapsule according to any one of claims 1 to 4, wherein X is CF ₃ SO ₃ ^" or BARF ^" and said nanocapsule is formed by eight counterions.

6. Nanocapsule according to any one of claims 1 to 5, wherein each Ri independently represents hydrogen or fluorine.

7. Nanocapsule according to any one of claims 1 to 6, wherein all the Ri are hydrogen.

8. Nanocapsule according to any one of claims 1 to 7, wherein each R ₂ independently represents a hydrogen or an alkyl group (d-C ₄ ).

9. Nanocapsule according to any one of claims 1 to 8, wherein all R ₂ are methyl.

10. Nanocapsule according to any one of claims 1 to 9, wherein each R ₃ independently represents a hydrogen or an alkyl group (d-C ₄ ).

eleven . Nanocapsule according to any one of claims 1 to 10, wherein all R ₃ are methyl.

12. Nanocapsule according to any of claims 1 to 1 1, wherein each R ₄ independently represents hydrogen or fluorine.

13. Nanocapsule according to any of claims 1 to 12, wherein all R ₄ are hydrogen.

14. Nanocapsule according to any one of claims 1 to 13, wherein M is Pd or Cu and IW is Zn or Pd.

15. Nanocapsule according to any of claims 1 to 14, wherein n is 2.

16. Nanocapsule according to any one of claims 1 to 15, wherein Ri is hydrogen, R ₂ and R 3 are methyl, R ₄ is hydrogen, M is Pd, I is Zn, n is 2 and

17. Nanocapsule according to any one of claims 1 to 15, wherein R 1 is hydrogen, R ₂ and R 3 are methyl, R ₄ is hydrogen, M is Cu, I is Pd, n is 2 and

18. Use of the nanocapsule according to any of claims 1 to 17, for the separation and / or purification of fulerenes.

19. Use of the nanocapsule according to any of claims 1 to 17, for the separation and / or purification of fulerenes of size between C60 and C84, both included, when n is 2.

20. Use of the nanocapsule according to any of claims 1 to 14, for the separation and / or purification of fulerenes of a size smaller than C60, when n is 1.

twenty-one . Use of the nanocapsule according to any of claims 1 to 14, for the separation and / or purification of fulerenes of a size greater than C84, when n is 3.

22. Method of encapsulation of fulerenes of size between C60 and C84, both included, comprising the following steps:

 to. dissolve a nanocapsule formed by two parallel (metal) tetracarboxylated porphyrins of general formula (I) joined by four metal macrocyclic compounds of general formula (II) via M-carboxylate bond, and counterions (X):

wherein: Μ ', M, Ri, R ₂ , R 3 and R ₄ are defined in claims 1 to 17; and n is 2;

 with a solvent selected from acetonitrile, CH2CI2, acetone, methanol or any combination thereof; Y

b. add the dissolved nanocapsules from step (a) or the undissolved nanocapsules to the fulerenes dissolved in toluene, 1,2-dichlorobenzene, carbon disulfide or any combination thereof; or b '. add to the nanocapsules dissolved in step (a) to the solid-state fulerenes, without dissolving;

 where the proportion of the solvent of the fulerene of step (b) / solvent of the nanocapsule of step (a) is between 9/1 to 4/1 and the temperature at which the above steps are carried out is between 0 ° C and 50 ° C.

23. Method according to claim 22, wherein the rubber steels to be encapsulated are selected from C60, C70, C76, C78, C84 or any of their mixtures.

24. Method according to any of claims 22 or 23, wherein the solvent of step (a) is acetonitrile.

25. Method according to any of claims 22 to 24, wherein the solvent of step (b) is toluene.

26. Method according to any of claims 22 to 25, wherein the proportion of the solvent of the fulerene of step (b) / nanocapsule solvent of step (a) is 4/1.

27. Method according to any of claims 22 to 26, wherein the temperature is 20-30 ° C, preferably 25 ° C.

28. Method according to any of claims 22 to 27, wherein M 'is Zn, M is Pd, Ri and R ₄ are H, R ₂ and R 3 are methyl and X is BARF ^" of the nanocapsule of step (a).

29. Method according to any of claims 22 to 27, wherein M 'is Pd, M is Cu, R1 and R ₄ are H, R ₂ and R3 are methyl and X is CF3SO3 ^" of the nanocapsule of step (a).

30. Method for the separation of C60 from a mixture of fulerenes, comprising:

 to. encapsulating said fulerenes by the method described in claims 22 to 29; Y

 b. wash the encapsulated fulerenes of step (a) three times with a mixture of 1,2-dichlorobenzene: CS2 in a ratio of 1: 1 to 0: 1 and where the encapsulated fulerenes are supported on a filtration column.

31. A method for the selective and sequential separation of C60 and C70 from a mixture of rubber carriers comprising: separating the C60 size fulerene by means of steps (a) and (b) of the method described in claim 30; and c. The precipitate obtained in step (b) is suspended in toluene and treated with triflic acid.

32. A method according to any one of claims 22 to 31, further comprising a step in which the solid comprising nanocapsulated fulerene is dried and NEt ₃ is added and subsequently dissolved with CH ₃ CN for recovery of the nanocapsule.