Simultaneous Spin-Crossover Transition and Conductivity Switching in a Dinuclear Iron(II) Coordination Compound Based on 7,7′,8,8′-Tetracyano-p-quinodimethane

The reaction of Fe(OAc)₂ and Hbpypz with neutral TCNQ results in the formation of [Fe₂(bpypz)₂(TCNQ)₂](TCNQ)₂ ( 1 ), in which Hbpypz=3,5-bis(2-pyridyl)pyrazole and TCNQ=7,7′,8,8′-tetracyano-p-quinodimethane. Crystal packing of 1 with uncoordinated TCNQ and π–π stacking of bpypz⁻ ligands produces an extended two-dimensional supramolecular coordination assembly. Temperature dependence of the dc magnetic susceptibility and heat capacity measurements indicate that 1 undergoes an abrupt spin crossover (SCO) with thermal spin transition temperatures of 339 and 337 K for the heating and cooling modes, respectively, resulting in a thermal hysteresis of 2 K. Remarkably, the temperature dependence of dc electrical transport exhibits a transition that coincides with thermal SCO, demonstrating the thermally induced magnetic and electrical bistability of 1 , strongly correlating magnetism with electrical conductivity. This outstanding feature leads to thermally induced simultaneous switching of magnetism and electrical conductivity and a magnetoresistance effect.     

Synthesis,Crystal Structure,and Magnetic Properties of a Quasi-one-dimensional Compound Based on TCNQ

A novel compound, （IBzQI）（TCNQ）2 2 （IBzQ1=1-（4-iodobenzyl）quinolinium and TCNQ = 7,7,8,8-tetracyanoquinodimethane） has been fabricated and X-ray single-crystal structurally analyzed. This compound crystallizes in the triclinic system, space group P1 with a = 8.3540（17）, b = 13.284（3）, c = 16.185（3） А, α= 82.12（3）, β= 75.19（3）, γ= 72.34°, V = 1651.2（6） А^3, Z= 2, C_40H_21IN_9, Mr = 754.56, Dc = 1.518 g/cm^3,μ= 1.015 mm^-1, S = 1.010, F（000） = 754, R = 0.0387 and wR = 0.0948. The structure analysis shows that the anions are stacked into column with tetrads, and there are two types of TCNQ entries （TCNQ-1 and TCNQ^0） in agreement with the IR spectra analysis of the compound. The temperature dependence of the magnetic susceptibility （2-300 K） for 2 exhibits spin gap of singlet-triplet feature, and the best fit gave △/kB = 1523.4 K. In order to understand both magnetic behavior and local charge distribution of [（TCNQ）2]-unit, the molecular orbital calculations and analysis based on extended Hückel method were performed, and the results support the analyses of both crystal structure and IR spectra.     

Synthesis and structure of the molecular complex between N-(N′, N′-dimethylaminopropyl)phenothiazine hydrochloride and 7,7,8,8-tetracyano-p-quinodimethane (DAPP-TCNQ)

Synthesis, spectroscopic, and X-ray structural analysis of the molecular complex between the N-(N, N-dimethylaminopropyl)phenothiazine hydrochloride, monohydrate, (DAPP) and 7,7,8,8-tetracyano-p-quinodimethane (TCNQ), has been carried out. Crystals of C₂₉H₂₇N₆OSCl are monoclinic, P2₁/c,a=12.190(2),b=7.695(2),c=28.928(3)Å, =91.68(1)°. The molecular complex consists of DAPP as donor binding to TCNQ as acceptor by the thiazine central ring and one of the aromatic rings stacking in parallel planes along thec-axis with an interplanar separation of 3.24Å and 3.16Å, respectively. The electronic and epr spectra of the complex are discussed.     

Charge Transfer Complexes of Ketotifen with 2,3-Dichloro-5,6-dicyano-p-benzoquinone and 7,7,8,8-Tetracyanoquodimethane: Spectroscopic Characterization Studies

The reactions of ketotifen fumarate (KT) with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π acceptors to form charge transfer (CT) complexes were evaluated in this study. Experimental and theoretical approaches, including density function theory (DFT), were used to obtain the comprehensive, reliable, and accurate structure elucidation of the developed CT complexes. The CT complexes (KT-DDQ and KT-TCNQ) were monitored at 485 and 843 nm, respectively, and the calibration curve ranged from 10 to 100 ppm for KT-DDQ and 2.5 to 40 ppm for KT-TCNQ. The spectrophotometric methods were validated for the determination of KT, and the stability of the CT complexes was assessed by studying the corresponding spectroscopic physical parameters. The molar ratio of KT:DDQ and KT:TCNQ was estimated at 1:1 using Job’s method, which was compatible with the results obtained using the Benesi–Hildebrand equation. Using these complexes, the quantitative determination of KT in its dosage form was successful.     

桂利嗪的荷移分光光度法测定

本研究了桂利嗪与７．７,８,８－四氰基对二次甲苯醌（ＴＣＮＱ）的荷移（ＣＴ）反应,确定了荷移反应的最佳条件。结果表明：在丙酮－甲醇介质中,二于室温条件下１０ｍｉｎ即可形成１：１的络合物,在其最大吸收波长７４３ｎｍ处表观摩尔吸光系数ε＝１．５８×１０＾４Ｌ·ｍｏｌ＾－１·ｃｍ＾－１,在０～１８μｇ·ｍＬ＾－１范围内符合比尔定律。方法的相对标准偏差小于３％（ｎ＝１０）。对形成ＣＴ络合物的机理进行了     

两种新型电荷转移盐的合成和光谱研究

合成了两种新的有机盐[NO₂BzPy]Cl(1)和[NO₂BzPyNH₂]Cl(2),(1)[或(2)]与K[TCNQ]₂进一步反应生成[NO₂BzPy] [TCNQ]₂ (3)和[NO₂BzPyNH₂] [TCNQ]₂(4)。光谱数据表明：TCNQ盐中存在TCNQ0和TCNQ-,并形成了一维TCNQ分子柱,且TCNQ₀和TCNQ-之间存在相互作用,部分电荷从[TCNQ]-₂向阳离子([NO₂BzPy]+和[NO₂BzPyNH₂]+)转移。     

阿奇霉素含量的荷移光谱法测定

用分光光度法分别研究了阿奇霉素与7,7,8,8-四氰基对二次甲基苯醌(TCNQ)和氯冉酸(CL)之间的荷移反应。实验表明：阿奇霉素与TCNQ间的反应在丙酮介质中进行,形成的络合物在743和842 nm有两个吸收峰,表观摩尔吸光系数分别是2.7×104 L·mol-1·cm-1和5.0×104 L·mol-1·cm-1;阿奇霉素与氯冉酸的反应在丙酮介质中进行,形成的络合物在530 nm处有吸收峰,表观摩尔吸光系数2.4×103 L·mol-1·cm-1。用摩尔比法和等摩尔连续变化法测得荷移络合物中阿奇霉素与配体的摩尔比均为1∶2。用以上两种方法测定了阿奇霉素片剂中阿奇霉素的含量,相对标准偏差为1.0%～1.4%(n=6),回收率为97%以上,与标准方法比较结果准确。     

Solitons in Polyacetylene Induced and Probed by Positive Mupons

Abstract

Positive muons were injected into both trans- and cis- (CH) as well as (CD)_x. In cis-polyacetylene, the μ⁺ was found to form a radical state with an unpaired electron localized near the μ⁺ In trans-polyacetylene, the longitudinal μ⁺ spin relaxation rate at 293 K showed H^?1/2 dependence on the applied field H. After considering possible mechanisms, we concluded that it is due to the soliton-like one-dimensional motion of induced unpaired electron.     

Electron transfer reactions of (C5R5)2(CO)2Ti (R=H or Me) with TCNE or TCNQ: Spectroelectrochemical assignment of metal and ligand oxidation states in [(C5Me5)2(CO)Ti(TCNX)]

The TCNX ligands TCNE (tetracyanoethene) and TCNQ (7,7,8,8-tetracyano-p-quinodimethane) react instantaneously with (C₅R₅)₂(CO)₂Ti, R=H or Me, to yield highly air-sensitive mononuclear complexes (C₅R₅)₂(CO)Ti(TCNX) of which the soluble species (R=Me) were characterized also in the oxidized and reduced forms through cyclic voltammetry, EPR, IR and UV-vis spectroelectrochemistry. While oxidation at rather low potentials yields labile carbonyltitanium(IV) species of the TCNX⁻ ligands, the reduction occurs stepwise at unusually negative potentials, first on the ligand (to yield coordinated TCNX²⁻) and then on the metal (to form Ti^II). For the neutral complexes (C₅R₅)₂(CO)Ti^2+q(TCNX^−q) the results support a rather large amount of charge transfer 1<q<2 from the metal to the acceptors TCNX. Evidence for the previously formulated {(μ-TCNE²⁻)[(C₅H₅)₂Ti^IV(CO)]₂}(TCNE²⁻) could not be found. The complexes (C₅R₅)₂(CO)Ti(TCNE) are compared with related compounds (C₅R₅)₂BrV(TCNE), (C₆R₆)(CO)₂Cr(TCNE) and (C₅R₅)(CO)₂Mn(TCNE).     

等离子体聚合膜的电学性质研究：Ⅰ.TCNQ聚合膜的结构和电学性质

本文采用内部电极、电容耦合式钟罩型射频等离子体聚合装置,首次进行了四氰代对二次甲基苯醌(TCNQ)的等离子体聚合,得到了电导率为10~(-8)～10~(-6)Scm~(-1)的聚合物半导体薄膜。由这些聚合物薄膜制备的Al/聚合膜/ITO(铟锡氧化物透明电极)夹层元件显示出整流特性和光生伏打效应。这种聚合物薄膜还具有光电导性质。红外光谱(IR)、紫外光谱(UV)的研究结果表明,优良的半导体特性归因于聚合膜中存在有较大范围的π电子共轭结构。