Electroactive Benzothiazole Hydrazones and Their [Mo₆O₁₉]²⁻ Derivatives: Promising Building Blocks for Conducting Molecular Materials

Abstract

The electroactive benzothiazole hydrazone AMBTH-H(2), a new member of the 2,2'-azino-bis(N-alkylbenzothiazole) family, was synthesised in a five-step procedure and characterised by using X-ray diffraction along with two intermediates and the N-methylbenzothiazole hydrazone MBTH-H(2). Both AMBTH-H(2) and MBTH-H(2) were coupled to [Mo(6)O(19)](2-) in acetonitrile in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine to give two new diazoalkane-hexamolybdates, which were isolated as tetrabutylammonium salts and characterised by using IR, UV/Vis and NMR spectroscopies, cyclic voltammetry and, for one of them, X-ray diffraction. The packing arrangement molecules in crystals of AMBTH-H(2), the redox features of the AMBTH-hexamolybdate hybrid together with a good electronic communication between the organic pi system and the molybdenum centres make these compounds very promising blocks for the synthesis of conducting molecular materials.

Microwave assisted synthesis of a mono organoimido functionalized Anderson polyoxometalate

“…36 Regarding functionalization of the lindqvist structural class, several examples have been isolated through a range of methods. 25,37,38 Typically, these methods involve the use of some form of activating agent such as DCC for the preparation of organo-imido derivatives from organic amine precursors. Notably in 2010, Wei successfully prepared [Mo 6 O 18 NC-(OCH 2 ) 3 MnMo 6 O 18 (OCH 2 ) 3 CNMo 6 O 18 ] 7− which was the first time a Mn-Anderson had been coupled to the hexamolybdate lindqvist polyanion.…”

Protonolysis of [(iPrO)TiMo5O18]3−: access to a family of TiMo5Lindqvist type polyoxometalates

“…(TBA) 3 2 was prepared by a hydrolytic aggregation reaction from (TBA) 2 [Mo 2 O 7 ], (TBA) 4 a-[Mo 8 O 26 ] and Ti(O i Bu) 4 according to eqn (1) as described previously for (TBA) 3 1. 6 The FTIR, 1 H, 13 C and 17 O NMR spectra of (TBA) 3 2 are all consistent with a structure that is analogous to that of 1, although its high solubility has so far prevented the growth of single crystals for single-crystal X-ray crystallography and purification for elemental analysis.…”

“…NMR spectra were recorded on a Bruker Avance 300 spectrometer operating at 300.0 MHz ( 1 H) or 75.39 MHz ( 13 C), or a Jeol Lamda 500 spectrometer operating at 500.0 MHz ( 1 H), 125.65 MHz ( 13 C) or 67.63 MHz ( 17 O). Resonances due to n Bu 4 N + cations are not listed below, but appear as multiplets centred at about 1.0, 1.4, 1.7 and 3.2 ppm in 1 H NMR spectra and as singlets at about 13, 19, 24 and 58 ppm in 13 C{ 1 H} NMR spectra. Two-dimensional 1 H EXSY NMR spectra were obtained at 500 MHz using a 90 •t 1 -90 •t mix -90 • -Acq(t 2 ) sequence with appropriate phasecycling to give a phase sensitive spectrum.…”

“…As part of our programme to develop the metalorganic chemistry of POMs, 2-8 we chose as basic structural units the comparatively simple group 6 Lindqvist type hexametalates [M 6 O 19 ] 2-(M = Mo, W) because of their ready formation in organic solvents. 9 Metathesis of oxido ligands in [Mo 6 O 19 ] 2has been achieved in reactions involving Ph 3 P NX (X = Ar, N C(Me)Ar), 10 ArNCO, 11 RNCO 2b or ArNH 2 , 3 and the latter reaction has subsequently been adapted to provide general access to arylimido and diazoalkane derivatives, 12, 13 but the tungstate [W 6 O 19 ] 2is inert under similar reaction conditions. The limited reactivity of these hexametalates has been ascribed to their low surface charge density and many of the reported organic derivatives have been prepared by indirect routes i.e.…”

Anderson-Type Polyoxometalates Functionalized by Tetrathiafulvalene Groups: Synthesis, Electrochemical Studies, and NLO Properties

“…It can however be noted that the coupling of an electroactive organic molecule and a POM was already successfully achieved in the [Mo6O18(AMBTH)] 2and [Mo6O18(MBTH)] 2hybrids where AMBTH and MBTH are benzothiazole hydrazone derivatives. 25 Here, we describe the synthesis and characterization of three new compounds associating via covalent bonds an Anderson POM platform and TTF organic molecules and in one case an additional SP moiety. Their electrochemical and spectroelectrochemical properties have been thoroughly investigated together with their second order non-linear optical properties.…”