Molecular photochromic ferromagnetic based on the layered polymeric tris-oxalate of Cr(III), Mn(II) and 1-[(1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-indoline]-8-yl)methyl]pyridinium

doi:10.1016/j.molstruc.2006.04.008

Journal of Molecular Structure

Volume 826, Issues 2–3, 29 January 2007, Pages 69-74

https://doi.org/10.1016/j.molstruc.2006.04.008 Get rights and content

Abstract

Basing on 1-[(1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-indoline]-8-yl)methyl] pyridinium chloride, a new bifunctional compound C₃₁H₂₆N₃O₁₆CrMn has been synthesized, which exhibits ferromagnetic (T_k = 5.1 K) and photochromic properties in the solid state.

Introduction

During the latest decades, the improvement of characteristics of monofunctional materials for molecular electronics, namely, organic photochromic materials, molecular magnetic materials and materials with non-linear optical properties (NLO) has reached its limit. At present, the development and practical application of new hybrid polyfunctional materials is of big interest for scientists. In this context, synthesis of molecular crystals uniting two functional sub-lattices with different properties appears to be promising. Anions of mono- and bi-metallic oxalate complexes C⁺[M^IIM^III(C₂O₄)₃]⁻, which are efficient bridging ligands for transferring magnetic interactions between metallic ions and therefore helpful for synthesis of molecular magnetics, are used as a magnetic sub-lattice. Replacement of a “non-functional” organic cation C⁺ by a functional cation is the main method for synthesis of hybrid materials. In particular, by using spiropyran (SP) and spirooxazine (SO) molecules in a cationic form (SP⁺ and SO⁺), a photochromic fragment can be incorporated in the molecular magnetic [1], [2], [3]. Recently, many investigations have been performed on the replacement of C⁺ by hyper-polarized organic molecules with NLO properties. Chromophores of stylben type are mainly used as such molecules [4], [5], [6]. Recently, the replacement of C⁺ by organic conductors [7], e.g., BEDT-TTF (bis(ethylenedithio)tetrathiofulvalene) [8], has been reported.

However, investigations in this field are still at their early stage. The basic problem is that replacement of a “non-active” ion by an “active” one, with essentially different structure, results in the change of the crystal structure in whole, with both sub-lattices losing their properties. Insertion of a photochromic SP or SO sub-lattice is also difficult for the following reason: SP and SO photochromic transformations need a considerable free volume, and in the crystalline state they are generally impeded. Recently, we have shown that SP⁺X⁻ salts have a specific crystalline structure, which provides photochromic transformations in crystals and depends little on X atom size [9], [10]. Taking into account that a two-dimensional magnetic structure of the anionic sub-lattice of bimetallic oxalates [M^IIM^III(OX)₃]⁻ allows varying of C⁺ size in a wide range, synthesis of hybrid crystalline materials containing a photochromic cationic SP⁺ or SO⁺ sub-lattice and a magnetic anionic [M^IIM^III(OX)₃]⁻ one looks promising.

As distinct from [1], [2], in this work photochromic 1-[(1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-indoline]-8-yl)methyl] pyridinium chloride (I) has been synthesized, which contains a quaternary pyridinium fragment not in the conjugated ring, but in a side aliphatic chain, and the latter was used as a basis for synthesis of molecular photochromic ferromagnetic C₃₁H₂₆N₃O₁₆CrMn (II).

Section snippets

Experimental

1-[(1′,3′,3′-Trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-indoline]-8-yl)methyl] pyridinium (1) was synthesized according to Scheme 1.

The solution of 0.35 g (2 mmol) of 2-methyleneindoline 4 in 2 ml of MeOH was added to the boiling mixture of 0.59 g (2 mmol) of aldehyde 3 and 14 ml of MeOH during 30 min. The mixture was boiled for 4 h, the solvent was evaporated, and the residue was re-crystallized from propanol-2. Yield 0.64 g, 71%. (Found: C, 66.89; H, 5.55; N, 9.46. Calcd. for C₂₅H₂₄ClN₃O₃: C, 66.74;

Synthesis

Synthesis of cationic spiropyran I by the interaction of pyridine and 8-chloromethyl-6-nitro-spirobenzopyran-indoline [12], [13] (the latter one obtained by condensation of 1,3,3-trimethyl-2-methyleneindoline with 3-chloromethyl-2-hydroxy-5-nitrobenzaldehyde [11]) was described in [12]. In contrast to the technique of [12], [13], we synthesized spiropyran I by condensation of pyridiniuim methyl-substituted aldehyde 3 with methylene base 4 (Scheme 1). Pyridiniuim methyl-substituted aldehyde 3

Conclusion

In this work, spiropyran salt 1-[(1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-indoline]-8-yl)methyl] pyridinium chloride has been synthesized and its photochemical properties have been studied, and a new bifunctional compound C₃₁H₂₆N₃O₁₆CrMn having ferromagnetic (T_k = 5.1 K) and photochromic properties in the crystalline state has been obtained on its basis. Both sub-lattices preserve the properties of the initial salts. Photochromic properties of polycrystals are reversible. Stability of

Acknowledgements

The authors are grateful to E.V. Antipov and A.V. Mironov for studying the samples by diffractometry method. The work has been supported by RFBR, Grant 03-03-32194, and the program of the Presidium of RAS “The target synthesis of substances with desired properties and development of functional materials on their basis”.

References (20)

S.M. Aldoshin et al.
J. Mol. Struct.
(2005)
S. Decurtins et al.
Inorg. Chim. Acta
(1994)
I. Kashima et al.
Synthetic Metals
(2005)
M. Okubo et al.
Solid State Commun.
(2005)
S. Benard et al.
Chem. Mater.
(2001)
S. Benard et al.
Chem. Commun.
(2000)
J.-P. Sauvage
(2001)
S. Benard et al.
Adv. Mater.
(1997)
S. Benard et al.
Adv. Mater.
(2000)
S. Benard et al.
J. Am. Chem. Soc.
(2000)

There are more references available in the full text version of this article.

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Molecular photochromic ferromagnetic based on the layered polymeric tris-oxalate of Cr(III), Mn(II) and 1-[(1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-indoline]-8-yl)methyl]pyridinium

Abstract

Introduction

Section snippets

Experimental

Synthesis

Conclusion

Acknowledgements

J. Mol. Struct.

Inorg. Chim. Acta

Synthetic Metals

Solid State Commun.

Chem. Mater.

Chem. Commun.

Adv. Mater.

Adv. Mater.

J. Am. Chem. Soc.