A New Type of Charge-Transfer Salts Based on Tetrathiafulvalene–Tetracarboxylate Coordination Polymers and Methyl Viologen

Abstract

Although charge-transfer compounds based on tetrathiafulvalene (TTF) derivatives have been intensively studied, {[cation](n+)·[TTFs](n-)} ion pair charge-transfer (IPCT) salts have not been reported. The aim of this research is to introduce functional organic cations, such as photoactive methyl viologen (MV(2+)), into the negatively charged TTF-metal coordination framework to obtain this new type of IPCT complex. X-ray structural analysis of the four compounds (MV)2[Li4(L)2(H2O)6] (1), {(MV)(L)[Na2(H2O)8]·4H2O}n (2), {(MV)[Mn(L)(H2O)2]·2H2O}n (3), and {(MV)[Mn(L)(H2O)2]}n (4), reveals that the electron donor (D) TTF moiety and the electron acceptor (A) MV(2+) form a regular mixed-stack arrangement in alternating DADA fashion. The TTF moiety and the MV(2+) cation are essentially parallel stacked to form the column structures. The strong electrostatic interaction is a main force to shorten the distance between the cation and anion planes. Optical diffuse-reflection spectra indicate that charge transfer occurs in these complexes. The ESR and magnetic measurements confirm that there is strong charge-transfer-induced partial electron transfer. Compounds 2, 3, and 4 show an effective and repeatable photocurrent response. The current intensities of 3 and 4 are higher than that of 2, which reflects that the coordination center of the Mn(II) ion has a great effect on the increasing photocurrent response.

Quaternary Phosphorus‐Induced Iodocuprate(I)‐Based Hybrids: Water Stabilities, Tunable Luminescence and Photocurrent Responses

“…On the contrary, 4 increases gradually and stabilizes after four cycles. The photocurrents of 1 , 3 and 4 all stabilize at about 4.40 × 10 –7 , 4.55 × 10 –7 and 4.75 × 10 –7 A, respectively The current intensities of this work are weaker than the other viologen‐containing compounds, such as (MV) 2 [Li 4 (L) 2 (H 2 O) 6 ] and MV[Ni(4‐pedt) 2 ] 2 , but stronger than metalloviologen‐containing hybrids . It has been proved that that the pure organic‐coated sole system shows no photocurrent response, therefore, in this work, iodocuprate–quaternary phosphorus donor–acceptor systems are the reason for photocurrent generation.…”

Crystal Structures, Gas Adsorption, and Electrochemical Properties of Electroactive Coordination Polymers Based on the Tetrathiafulvalene-Tetrabenzoate Ligand

“…26 This resulted in a number of TTF-based complexes including monocarboxylate, 27,28 dicarboxylate [29][30][31][32] and tetracarboxylate ligands. [33][34][35][36][37][38][39][40] These types of coordination compounds containing TTF are also particularly attractive for fundamental electrochemical studies.…”

<p>Multifunctional Quaternary Phosphorus/Bromoargentate Hybrids: The Achievement of Greenish Blue Luminescence, Repeatable Photocurrent Responses and Durable Antimicrobial Activities with Enhanced Water Stability</p>

“…Their photocurrents stabilize at approximately 1.10×10 −7 (for 1 and 2 ) and 1.30×10 −7 A (for 3 ), which are weaker than those of viologen-containing compounds, such as (MV) 2 [Li 4 (L) 2 (H 2 O) 6 ] and MV[Ni(4-pedt) 2 ] 2 . 45 It is universally accepted that the pure organic-coated system did not show any photocurrent response, 46 so the bromoargentate/phosphonium donor–acceptor systems are responsible for the photocurrent generation in this work. Consequently, its photoinduced current generation mechanism is given: first, the photosensitive phosphonium cations are irradiated to generate the (Ph 3 -R-Ph 3 ) 2+ • radicals, and at the same time, Ag x Br y (y-x)- donors also transfer electrons to phosphoniums with production of Ag x Br y (y-x)- • radicals.…”