ES2239901A1 - Metalodendrites - Google Patents

Abstract

The invention relates to novel hyperbranched molecules, the structure of which incorporates metals known as metalodendrites, having a conformation which changes in a reversible manner in response to a redox stimulus, and to the use of same as molecular switches. Said metalodendrites preferably contain structural ferrocene/ferrocenium units.

Description

Metallodendrites

Field of the Invention

The invention relates in general to new hyperbranched molecules that incorporate metals into their structure, called metallodendrites, whose conformation changes shape reversible against a red-ox stimulus. Likewise, The invention relates to its use as switches molecular.

Background of the invention

Hyperbranched macromolecules, called dendrimers, that incorporate one or more metals in their structure have specific physico-chemical characteristics that allow them to be easily used as molecular switches. The interest in their development is based on the ability to obtain highly ordered materials with electronic and optical magnetic properties of technological interest, and in this sense, in their use as molecular switches. The term molecular switch is defined as a set of discrete molecular systems that allows mechanical movements (output) when they are subjected to an external stimulus
(input).

Peruga, A., et al ., J. Organometallic Chem., 637-639 (2001) 191-197, "Facile synthesis of two-dimensional ferrocenyl-based branched oligomers by palladium-catalyzed coupling reactions", describes a procedure for the synthesis of a metallodendrite. Said metallodendrite is a two-dimensional metal complex in the form of a star, which in the face of a red-ox stimulus increases its molecular dimensions by stretching out the repulsion that occurs between ferrocenes that contain Fe 2+ atoms and that are oxidized to Fe 3+. This metallodendrite has a number of drawbacks, such as its very limited solubility to certain solvents or reaction media. Therefore it cannot be used in solution in any reaction medium in which it is not soluble. Likewise, this metallodendrite is not stable in all the reaction media in which it could be used, and the variation it suffers from its molecular dimensions in response to a red-ox stimulus is not sufficiently marked.

It would be important to get switches Molecules easy to synthesize, soluble in different media and that present a significant variation, for example in their dimensions, versus redox variations.

There is therefore a need to provide, alternative metallodendrites that exceed part or all of the drawbacks of the state of the art and that therefore They can have an industrial application.

Compendium of the invention

The present invention faces the problem of provide an alternative metallodendrite that exceeds part or the all the disadvantages of the metallodendrite of the state of the technique, mentioned above.

The solution provided by the present invention is based on the fact that the inventors have observed that on the one hand it is possible to modulate the solubility in the different solvents of the metallodendrites by introducing groups or substituents, that do not produce a steric hindrance that prevents their change conformational Also, the inventors have observed surprisingly that when the ferrocene elements are placed, In addition to the periphery, the center of the structure is produced a much more drastic, unidirectional conformational change.

Therefore in one aspect the invention provides a new metallodendrite selected from the group of the metallodendrites A) with a two-dimensional, symmetrical structure (Formula 1) and the group of metallodendrites B) which additionally to the ferrocenes in said hyperrramifications comprise a central ferrocene (Formula 2).

Among the advantages of the new metallodendrites the possibility of selecting a specific one can be mentioned metallodendrite with certain solubility characteristics depending on the reaction medium in which it is desired to apply. Other additional advantage of these metallodendrites is that both those of group A), for having a larger core core, such as of group B) due to the presence of a central ferrocene, they present a greater molecular size and a response in conformational change more drastic Additionally, metallodendrites with a ferrocene central group B) suffer a unidirectional conformational change 100%, which increases your chance of response enormously.

Brief description of the figures

Figure 1. Represents the synthesis scheme of a metallodendrite of group B) and conformational change reversible suffering from a stimulus red-ox.

Description of the invention

The present invention provides a metallodendrite selected from group A) or B) where:

the metallodendrites of group A) present the Formula 1:

Formula one

one

where, one or more of the hydrogenic substituents present therein can be independently substituted by one or more substituents selected from the group consisting of halogens, R groups, aryl, -OH, -OR, -COOH, -COOR, -OCOR, -CHO, -SO3H, -CN, -COR, -CH_ {NR} {1} R2 where R is selected from the group formed by the linear C 1 -C 6 alkyl groups, branched and cyclic, and where R1 and R2 can be independently same or different from each other, hydrogen or a group R;

Fc is the structure (η 5 -C 5 H 5) - M - (η 5 -C 5 H 4) -, where M is a metal coordinated to the two rings of cyclopentadienyl (η 5 -C 5 H 5) and (η 5 -C 5 H 4), selected from Fe, Ni, Co, Zr, Ru, Cr, Zr, Hf, Ti, Mo, Nb, W and V; Y

the metallodendrites of group B) present the following structural formula:

Formula 2

2

where one or more of the hydrogenic substituents present therein can be independently substituted by one or more substituents selected from the group consisting of halogens, R groups, aryl, -OH, -OR, -COOH, -COOR, -OCOR, -CHO, -SO3H, -CN, -COR, -CH_ {NR} {1} R2 where R is selected from the group formed by the linear C 1 -C 6 alkyl groups, branched and cyclic, and where R1 and R2 can be independently same or different from each other, hydrogen or a group R;

Fc is the structure (η 5 -C 5 H 5) - M - (η 5 -C 5 H 4) -, where M is a metal coordinated to the two rings of cyclopentadienyl (η 5 -C 5 H 5) and (η 5 -C 5 H 4), selected from Fe, Ni, Co, Zr, Ru, Cr, Zr, Hf, Ti, Mo, Nb, W and V; Y

the central iron atom can be a metal other than Fe selected from Ni, Co, Zr, Ru, Cr, Zr, Hf, Ti, M or, Nb ,. W and V. Also, the number of structural units [-CH = CH-C 6 C 4 -], ie rings benzene separated by double bonds C = C, in these branches It can be between 1 and 5.

The substituents on the metallodendrite of group A) or on the metallodendrite of group B) are preferably substituents that do not imply impediments we are in the change conformational of them, and that can reduce their ability to undergo a maximum conformational change.

In a particular embodiment Fc represents ferrocene-ferrocinium. In another embodiment In particular, the metallodendrite of group B) has an atom of Fe in the center of it.

These new metallodendrites provided by the present invention, hereinafter metallodendrites of the invention, react reversibly to a stimulus red-ox. The red-ox stimulus is any combination of an oxygen entity and a reducing agent, so that the oxidizing agent is able to oxidize the metallodendrite, in particular, metal atoms from a state of initial oxidation at a higher oxidation state and, at then the reducing agent is able to reduce the atoms of metal to the initial oxidation state. The oxidation of said metal atoms causes an increase in the positive charge on the metallodendrite and this leads to a strong electrostatic repulsion among them, which leads to a significant increase in the size of the same and the conformational change to minimize these repulsions

This type of metallodendrites that react from Reversible form are used as molecular switches. Bliss reversibility has been proven by voltammetry studies cyclic

The type of conformational change undergone by a metallodendrite of group A) is two-dimensional resulting in an elongation of the ramifications. In the metallodendrites of group B) (see Figure 1) this change is much more drastic, since the central structural element ferrocene - (η 5 -C_ {5} H_ {4}) - M- \ eta ^ {5} -C_ {5} H4} -, rotates on itself, as a hinge, causing an anti- conformation, fully expanded in only one direction. The conformational changes have been verified by spectroscopic characterization techniques, in particular nuclear magnetic resonance imaging (NMR) and X-ray diffraction. The metallodendrites of group B) have two identical branches, which overlap so that the benzenes also overlap contributing to their great stability in their folded conformation. Said overlapping of the benzene rings stabilize the structure by means of pi-pi interactions. The greater the number of benzene rings in each branch, the greater the stability of the metallodendrite.

The metallodendrites are obtained by general procedure described in the reference mentioned characterized by the use of the sin-di catalyst m-chloro) -bis [o- (benzylphenylphosphine) benzyl] dipaladium (II). Two particular embodiments of the procurement procedure are described later (see Examples 1 and 2). Any variant for another particular embodiment is evident for a subject matter expert in view of the aforementioned document and the common general knowledge.

The metallodendrites of the invention have Application as molecular switches. The applications of these new metallodendrites derive from the properties particular of them, since they offer the possibility of prepare conjugated systems that offer the possibility of communication, electronics between the terminal subunits, being this of particular interest in terms of modulating properties Electronic materials. Among the applications of metallodendrites of the invention highlights its use as a sensor of red-ox processes, for example, as a sensor of the presence of carbon monoxide. Among other applications you can cite also its use in the design of scale machines molecular, in molecular detection systems, design of chemically controlled switches, storage information, among others.

The following illustrative examples of the invention should not be construed as limiting the scope of protection of it.

Examples Example 1 Synthesis of Fe {(η 5 -C 5 H 4) - CH = CH-C 6 H 4 -CH = CH-C 6 H 3 [- CH = CH - η 5 -C 5 H 4) 2] 2} 2

A suspension of olefin 1,3-bis {-CH = CH - (η 5 -C 5 H 4) - Fe - (η 5 -C 5 H 5)} - 5-CH 2 = CH-C 6 H 3 (200 mg, 0.4 mmol), Fe {(η 5 -C 5 H 4) - CH = CH-C 6 H 4 -Br} 2 (105 mg, 0.2 mmol), anhydrous sodium acetate (40 mg, 0.6 mmol), tetrabutylammonium bromide (40 mg, 0.2 mmol) and 20 mg of sin-di (m-chloro) -bis [o- (benzylphenylphosphine) benzyl] dipaladium (II) in DMA (N, N-dimethylcetamide) (12 ml) is heated at 130 ° C for 5 h. The reaction crude was taken to dryness under reduced pressure (13 mm Hg) and a extraction with water / dichloromethane. The organic phase was dried over magnesium sulfate and purified by column chromatography with silica gel using as eluent a mixture of hexane / dichloromethane in a 2: 1 ratio. The product was recrystallized using a dichloromethane / hexane mixture. He yield was 62%.

Figure 1 shows the schematized synthesis of said compound of the group of metallodendrites B), together with the conformational change undergone by said metallodendrite in presence of a red-ox stimulus.

3

Figure one

Example 2 Synthesis of (E, E) - {(η 5 -C 5 H 5) Fe (η 5 -C 5 H 4) - CH = CH - (η 5 -C 5 H 4) Fe (η 5 -C 5 H 4) - CH = CH-C 6 H 4 {3} -C_ {6} H_ {3}

A suspension of 0.5 mmol of (E) - (η 5 -C 5 H 5) Fe (η 5 -C 5 H 4) - CH = CH - (η 5 -C 5 H 4) Fe (η 5 -C 5 H 4) - CH = CH 2, 0.6 mmol of 1,3,5- (4-bromophenyl) benzene, 2.6 mmol of anhydrous sodium acetate, 0.2 mmol of tetrabutylammonium and 0.02 mmol of sin-di (m-chloro) -bis [o- (benzylphenylphosphine) benzyl] dipaladium (II) in DMF (N, N-dimethylformamide) was heated to 130 ° C for 20 hours. The reaction crude was taken to dryness. under reduced pressure (13 mm Hg) and extraction was performed with H 2 O / NaHCO 3 and CH 2 Cl 2. The organic phase dried over MgSO4 and purified by column chromatography with silica gel, using as eluent a mixture of hexane and CH 2 Cl 2 in a 1: 1 ratio. The yield was 80%.

Claims (6)

1. A metallodendrite selected from the group of metallodendrites A) of structural formula: Formula one 4 where, one or more of the hydrogenic substituents present therein can be independently substituted by one or more substituents selected from the group consisting of halogens, R groups, aryl, -OH, -OR, -COOH, -COOR, -OCOR, -CHO, -SO3H, -CN, -COR, -CH_ {NR} {1} R2 where R is selected from the group formed by the linear C 1 -C 6 alkyl groups, branched and cyclic, and where R1 and R2 can be independently same or different from each other, hydrogen or an R group; Y Fc is the structure (η 5 -C 5 H 5) - M - (η 5 -C 5 H 4) -, where M is a metal coordinated to the two rings of cyclopentadienyl (η 5 -C 5 H 5) and (η 5 -C 5 H 4), selected from Fe, Ni, Co, Zr, Ru, Cr, Zr, Hf, Ti, Mo, Nb, W and Y; Y a metallodendrite of group B) of formula structural: Formula 2 5 where one or more of the hydrogenic substituents present therein can be independently substituted by one or more substituents selected from the group consisting of halogens, R groups, aryl, -OH, -OR, -COOH, -COOR, -OCOR, -CHO, -SO3H, -CN, -COR, -CH_ {NR} {1} R2 where R is selected from the group formed by linear, branched and C1-C6 alkyl groups cyclic, and where R1 and R2 can be independently equal or different from each other, hydrogen or a group R; Fc is the structure (η 5 -C 5 H 5) - M - (η 5 -C 5 H 4) -, where M is a metal coordinated to the two rings of cyclopentadienyl (η 5 -C 5 H 5) and (η 5 -C 5 H 4), selected from Fe, Ni, Co, Zr, Ru, Cr, Zr, Hf, Ti, Mo, Nb, W and V; the central iron atom can be a metal other than Fe selected from Ni, Co, Zr, Ru, Cr, Zr, Hf, Ti, Mo, Nb, W and V; and the number of structural units [-CH = H-C 6 C 4 -], is between 1 and 5. 2. A metallodendrite according to claim 1, where Fc represents ferrocene-ferricinium. 3. A metallodendrite according to claim 1, where in the structure the metallodendrite of group B) presents a Atom of Faith in the center of it. 4. Use of a metallodendrite according to the claim 1, as molecular switch. 5. Use of a metallodendrite according to the claim 1, as a sensor for the detection of monoxide of carbon. 6. Use of a metallodendrite according to claim 1, in the design of molecular scale machines, in molecular detection systems, switch design Chemically controlled, and / or storage.