基于二-吡嗪-(2, 3-f: 2′3′-h)-喹喔啉和吡啶-2，5-二羧酸混合配体的两个新奇金属有机超分子骨架的水热合成、晶体结构与光致发光

以二-吡嗪-(2, 3-f: 2′3′-h)-喹喔啉(Dpq)和吡啶-2,5-二羧酸(2,5-H2pda)两种混合配体与不同金属硝酸盐为原料,通过水热反应得到了两个新奇的金属有机骨架[Zn2(Dpq)2(2,5-pda)2(H2O)2]·2H2O(1)和[Cd2(Dpq)2(2,5-pda)2]·2H2O(2),并经元素分析、TG、IR、X-射线单晶衍射分析进行了表征。结构分析表明,2,5-pda采取不同的配位方式桥连金属离子分别形成了二聚物1和2D菱形网络2。在化合物1中,相邻的二聚物通过氢键和π-π堆积作用形成扭曲的a-Po超分子结构。在化合物2中,相邻的配位聚合物层通过氢键拓展成扭曲的a-Po超分子骨架,而π-π堆积起到巩固骨架的作用。化合物1和2的结构差异表明了金属离子和配体在配位聚合物自组装过程中对结构的影响。此外固态标题化合物在室温下表现出蓝色的发光性质。     

Multifunctional materials based on polyazomethines derived from 2,5‐dihydroxy‐1,4‐benzoquinone and siloxane diamines

New polyazomethines have been synthesized by the reaction between 2,5‐dihydroxy‐1,4‐benzoquinone and siloxane diamines differing by the siloxane sequence length. A dimer has also been prepared as a model compound. The products were characterized by spectral (FTIR and ¹H‐NMR) and elemental analyses, GPC, viscosity measurements, solubility tests, and transmission electron microscopy (TEM). The different properties have been investigated by adequate techniques: thermal (DSC and TGA), spectral (UV–vis and fluorescence spectroscopy), redox (Differential Pulse Voltammetry). pH‐sensitivity and metal complexing ability were also evaluated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1862–1872, 2008     

Synthesis of 2,2,5,5‐Tetrasubstituted 1,4‐Dioxa‐2,5‐disilacyclohexanes via Organotin(IV)‐Catalyzed Transesterification of (Acetoxymethyl)alkoxysilanes

(Acetoxymethyl)silanes 2 , 7 a – c , and 10 a – c with at least one alkoxy group, of the general formula (AcOCH₂)Si(OR)_3?n(CH₃)_n (R: Me, Et, iPr; n=0, 1, 2), were synthesized from the corresponding (chloromethyl)silanes 1 , 6 a – c , and 9 a – c by treatment with potassium acetate under phase‐transfer‐catalysis conditions. These compounds were found to provide 2,2,5,5‐organo‐substituted 1,4‐dioxa‐2,5‐disilacyclohexanes 3 , 8 a – c , and 11 a – c if treated with organotin(IV) catalysts such as dioctyltin oxide. The reaction proceeds through transesterification of the acetoxy and alkoxy units followed by ring‐closure to form a dimeric six‐membered ring. The corresponding alkyl acetates are formed as the reaction by‐products. With these mild conditions, the method overcomes the drawbacks of previously reported synthetic routes to furnish 2,2,5,5‐tetramethyl‐1,4‐dioxa‐2,5‐disilacyclohexane ( 3 ) and even allows the synthesis of 1,4‐dioxa‐2,5‐disilacyclohexanes bearing hydrolytically labile alkoxy substituents at the silicon atom in good yields and high purity. These new materials were fully characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and X‐ray analysis (trans‐ 8 a ).     

Synthesis of (−)‐3‐Carene‐2,5‐dione via Allylic Oxidation of (+)‐3‐Carene

Activated carbon‐supported CuCl₂ (CuCl₂/AC) is a heterogeneous catalyst for the liquid‐phase selective allylic oxidation of (+)‐3‐carene with tert‐butyl hydroperoxide (TBHP) and O₂ to produce (?)‐3‐carene‐2,5‐dione. The possible reaction mechanism and the effects of different factors on the allylic oxidation were investigated. The optimal conditions are as follows: reaction temperature, 45 °C; molar ratio of CuCl₂ to (+)‐3‐carene, 1%; volume ratio of (+)‐3‐carene to TBHP, 1:3; and reaction time, 12 h. Under the optimal conditions, the conversion of (+)‐3‐carene reached 100%, whereas the selectivity for (?)‐3‐carene‐2,5‐dione reached 78%. The CuCl₂/AC catalyst was characterized via X‐ray diffraction, and the chemical structure of the target compound was identified via infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, mass spectrometry, and optical analysis.     

Lifetime Shortening and Fast Energy‐Tansfer Processes upon Dimerization of a A‐π‐D‐π‐A Molecule

Time‐resolved fluorescence and transient absorption experiments uncover a distinct change in the relaxation dynamics of the homo‐dimer formed by two 2,5‐bis[1‐(4‐N‐methylpyridinium)ethen‐2‐yl)]‐N‐methylpyrrole ditriflate ( M ) units linked by a short alkyl chain when compared to that of the monomer M . Fluorescence decay traces reveal characteristic decay times of 1.1 ns and 210 ps for M and the dimer, respectively. Transient absorption spectra in the spectral range of 425–1050 nm display similar spectral features for both systems, but strongly differ in the characteristic relaxation times gathered from a global fit of the experimental data. To rationalize the data we propose that after excitation of the dimer the energy localizes on one M branch and then decays to a dark state, peculiar only of the dimer. This dark state relaxes to the ground state within 210 ps through non‐radiative relaxation. The nature of the dark state is discussed in relation to different possible photophysical processes such as excimer formation and charge transfer between the two M units. Anisotropy decay traces of the probe‐beam differential transmittance of M and the dimer fall on complete different time scales as well. The anisotropy decay for M is satisfactorily ascribed to rotational diffusion in DMSO, whereas for the dimer it occurs on a faster time scale and is likely caused by energy‐transfer processes between the two monomer M units.     

1‐Phenyl‐1,2‐cyclohexadiene: Generation,Interception by Activated Olefins,Dimerisation and Trimerisation

Four possible precursors of 1‐phenyl‐1,2‐cyclohexadiene ( 2 ) were examined, namely, 6,6‐dibromo‐1‐phenylbicyclo[3.1.0]hexane, (1α,5α,6α)‐6‐bromo‐6‐fluoro‐1‐phenylbicyclo[3.1.0]hexane, 1‐bromo‐2‐phenylcyclohexene and 1‐bromo‐6‐phenylcyclohexene. All four compounds could be converted into 2 , as demonstrated by the products of the interception of 2 with activated olefins. Styrene, 1,1‐diphenylethene, indene, furan and 2,5‐dimethylfuran were employed as such. Whereas the first three gave [2+2] cycloadducts of 2 , the last two provided one [4+2] cycloadduct each. To create the [2+2] cycloadducts, the π bond of 2 that is more remote from the phenyl group reacted, whereas the π bond of 2 conjugated with the phenyl group exclusively produced the [4+2] cycloadducts. The generation of 2 in the absence of a trapping reagent brought about relatively good yields of a dimer or a trimer of 2 depending on the mode of the liberation of 2 . Being derivatives of triphenylene, the dimer as well as the trimer have unusual structures, thereby indicating that a phenyl group is participating in the formation of these compounds. The most surprising structure of the trimer was elucidated by X‐ray crystal diffraction. As to the mechanisms, diradical intermediates are proposed both for the cycloadditions and for the dimerisation. The initial steps of the latter seem to proceed also in the trimerisation.     

蝶形主体分子的设计、合成及其包结性能的研究

设计、合成了两种蝶形主体分子：2，5－二（三苯甲基）对苯二酚1，2，5－二（二苯甲基）对苯二酚2.1和2可与许多有机小分子形成配位包合物。用IR表征了主体分子1和2 的包结物， 用¹H NMR测定了主客体分子的摩尔比：1•DMF (1：2)，1•DMSO (1:2)，1 •吡啶 （1：2），1•环戊酮 （2：3）和2•DMF 1：2），2•DMSO （1：2），2 •THF （1：1），2•苯甲醛（1：2），2•苯乙酮 （1：2），2•2，5－己二酮 （1：1），2 •N－甲基－2－吡咯烷酮 （1：3）。单晶X-射线衍射分析了包结物2·苯甲醛的晶体结构，在分子间氢键的相互作用下晶体得以稳定。     

2,4‐Di­methoxy­benzoic acid and 2,5‐di­methoxy­benzoic acid

The title compounds (both C₉H₁₀O₄) have nearly planar structures, and the methyl and/or carboxylic acid groups lie out of the molecular plane, as dictated by steric interactions. 2,5‐Di­methoxy­benzoic acid (2,5‐DMBA) forms an unusual intramolecular hydrogen bond between the carboxylic acid group and the O atom of the methoxy group in the 2‐position [O⋯O = 2.547 (2) Å and O—H⋯O = 154 (3)°]. 2,4‐DMBA forms a typical hydrogen‐bond dimer with a neighboring mol­ecule.     

5‐Mercapto‐1,3,4‐thiadiazole‐2(3H)‐thione: Synthesis and Structure of Alkylated Derivatives

The observed structure of 1,3,4‐thiadiazolidine‐2,5‐dithione (also known as 2,5‐dimercapto‐1,3,4‐thiadiazole) has been previously reported in three different tautomeric forms including —dithiol and—dithione. This report examines the relative stability of each form and also reports synthesis and characterization of the structures of mono‐alkylated and di‐alkylated forms of 5‐mercapto‐1,3,4‐thiadiazole‐2(3H)‐thione. The methods of X‐ray crystallography, NMR spectroscopy, and ab initio electronic structure calculations were combined to understand the reactivity and structure of each compound.     

New one step synthesis of crown compounds containing a 1,3,4‐thiadiazole moiety

New macrocyclic polyether compounds containing a 2,5‐bis(2‐hydroxyphenyl)‐1,3,4‐thiadiazole moiety have been prepared by a nucleophilic substitution reaction involving ethylene or polyethylene glycol ditosylate and a bisphenol, the 2,5‐bis(2‐hydroxyphenyl)‐1,3,4‐thiadiazole, with solid anhydrous carbonate as a base. The structures of the macrocycles obtained were firmly established by ¹H and ¹³C nmr spectroscopy and their mass spectra.     

Blue photo‐ and electroluminescence based on poly(2‐benzoyl‐1,4‐phenylene) and poly(2,5‐dibenzoyl‐1,4‐phenylene)

Poly(2‐benzoyl‐1,4‐phenylene) (PBP) and poly(2,5‐dibenzoyl‐1,4‐phenylene) (PDBP) were synthesized by coupling polymerization using a Ni catalyst of 2,5‐dichlorobenzophenone and 2,5‐dichloro‐1,4‐dibenzophenone, respectively. These polymers are soluble in common organic solvents, have high thermal stability and show bright blue photoluminescence. Light‐emitting diodes fabricated with these polymers as the active layer emit blue electroluminescence with wavelength at 433 nm for PBP and 475 nm for PDBP. Copyright © 1999 John Wiley & Sons, Ltd.     

A facile method to synthesize high‐molecular‐weight biobased polyesters from 2,5‐furandicarboxylic acid and long‐chain diols

In this study, biobased furan dicarboxylate polyesters have been prepared using 2,5‐furandicarboxylic acid (FDCA) and diols with high number of methylene groups (long‐chain diols), namely, 8, 9, 10, and 12. Because of the high boiling points of these diols, a modified procedure of the well‐known melt polycondensation was applied in this work. According to this, the dimethyl ester of FDCA (DMFD) reacted in the first transesterification stage with the corresponding diols forming bis‐hydroxy‐alkylene furan dicarboxylates (BHFD). In the second stage, the BHFD reacted with DMFD again at temperatures of 150–170 °C (for 4–5 h), and in the final stage, the temperature was raised to 210–230 °C (vacuum was applied for 2–3 h). The molecular weight of the polyesters and the content of oligomers, as was verified by gel permeation chromatography analysis, depend on the polycondensation time and temperature. The chemical structure of the polyesters was verified from ¹H NMR spectroscopy. All the polymers were found to be semicrystalline, with melting temperatures from 69 to 140 °C depending on the diol used. In addition, the mechanical properties also varied with the type of diol. The higher values were observed for poly(octylene 2,5‐furanoate), whereas the lowest values were observed for poly(dodecylene 2,5‐furanoate) with the higher number of methylene groups in its repeating unit. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2617–2632     

NMR Study of Hetero‐Association Accompanying Self‐Association of 2‐Hydroxyl‐4‐methyl‐pyridine and 2‐Pyrrolidone in Acetonitrile

This work in vestigated not only the equilibrium of self‐association of 2‐pyrrolidone (A) and that of 2‐hydroxyl‐4‐methyl‐pyridine (B), but also the hetero‐association between A and B in [²H₃]acetonitrile through hydrogen bonding using high‐resolution nuclear magnetic resonance spectroscopy. Dilution shift data for the protons of the NH group of A and OH group of B were measured over a wide range of temperatures and concentrations. In addition, the monomer shifts, dimer shifts and dimerization constants of self‐association and hetero‐association were evaluated using a graphic method operating on the dilution chemical shift data. The enthalpy and entropy of dimerization of self‐association and hetero‐association were also obtained from the van't Hoff plot.     

Convenient Synthesis and Biological Activity of Mono and Diacyl 2,5‐Dimercapto‐1,3,4‐thiadiazole Derivatives

New derivatives of 2,5‐dimercapto‐1,3,4‐thiadiazole substituted both at one or two exocyclic sulfur atoms with a series of aroyl or ethoxycarbonyl groups were synthesized in reactions of 2,5‐dimercapto‐1,3,4‐thiadiazole salts with appropriate acid chlorides or ethyl chloroformate in mild conditions. The products were characterized by spectroscopy (¹H NMR, ¹³C NMR, IR, and HRMS). Some from the synthesized compounds were screened in vitro and in vivo for antibacterial and antifungal activities against a panel of reference strains of microorganisms. The study revealed that ethyl S‐(5‐mercapto‐1,3,4‐thiadiazol‐2‐yl) carbonothioate seems to be the most active and versatile compound against Gram‐positive bacteria, Gram‐negative bacteria, and plant pathogenic fungi.     

Syntheses,Structure, Electrochemistry,and Optical Properties of 1,3‐Diethyl‐2,3‐dihydro‐1‐H‐1,3,2‐pyrido‐[4,5‐b]‐diazaboroles

Reaction of 2,5‐bis(dibromoboryl)thiophene ( 4 ) or 1,4‐bis(dibromoboryl)benzene ( 6 ) with two equivalents of N,N′‐dilithiated 2,3‐diaminopyridine ( 3 ) led to the generation of the pyridodiazaboroles 5 and 7 in which the two diazaborole rings are linked by 2,5‐thiophen‐diyl or 1,4‐phenylene units via the boron atom. The novel compounds were characterized by elemental analyses and spectroscopy (¹H‐, ¹¹B‐, ¹³C‐NMR, MS, and UV‐VIS). The molecular structure of 5 was elucidated by X‐ray diffraction. Cyclovoltammograms of 5 and 7 show two irreversible oxidation waves at 0.76 and 0.73 V, respectively vs Fc/Fc⁺. The novel compounds display intense blue luminescence with Stokes shifts of 76 and 74 nm and relative quantum yields of 39 and 43 % vs Coumarin 120 (Φ = 50 %).     

Electrocatalytic Oxidation of 5‐(Hydroxymethyl)furfural Using High‐Surface‐Area Nickel Boride

The electrochemical oxidation of the biorefinery product 5‐(hydroxymethyl)furfural (HMF) to 2,5‐furandicarboxylic acid (FDCA), an important platform chemical for the polymer industry, is receiving increasing interest. FDCA‐based polymers such as polyethylene 2,5‐furandicarboxylate (PEF) are sustainable candidates for replacing polyethylene terephthalate (PET). Herein, we report the highly efficient electrocatalytic oxidation of HMF to FDCA, using Ni foam modified with high‐surface‐area nickel boride (Ni_xB) as the electrode. Constant potential electrolysis in combination with HPLC revealed a high faradaic efficiency of close to 100 % towards the production of FDCA with a yield of 98.5 %. Operando electrochemistry coupled to ATR‐IR spectroscopy indicated that HMF is oxidized preferentially via 5‐hydroxymethyl‐2‐furancarboxylic acid rather than via 2,5‐diformylfuran, which is in agreement with HPLC results. This study not only reports a low‐cost active electrocatalyst material for the electrochemical oxidation of HMF to FDCA, but additionally provides insight into the reaction pathway.     

2,5‐Dihydro‐1H‐imidazole‐Based Nitroxides as Prospective Mediators in Living Radical Polymerization

A number of spectroscopic methods were applied to obtain kinetic parameters of reactions modelling the 2,5‐dihydro‐1H‐imidazole 1‐oxide mediated living polymerization of acrylates. The homolysis rate constants of alkoxyamines based on five nitroxides were measured by EPR spectroscopy at different temperatures. The recombination rate constants k_c between the corresponding alkyl radicals and the nitroxides were measured by means of laser flash photolysis. The time‐resolved chemically induced dynamic nuclear polarization (TR‐CIDNP) experiments revealed the negligible contribution of disproportionation in the recombination reaction. In addition, the thermodecomposition of alkoxyamines in the NMR probe showed the absence of intramolecular elimination of hydroxylamines from the corresponding alkoxyamines. Analysis of the kinetic parameters showed that the 2,5‐dihydro‐1H‐imidazole 1‐oxide type radicals are promising mediators for the living polymerization of acrylates and methacrylates.     

Synthesis of soluble electron‐donating polymers containing vinylogous TTF by oxidative dimerization of 1,4‐bisdithiafulvenyl‐2,5‐dialkoxybenzene

A new electron‐donating polymer composed of a vinylogous tetrathiafulvalene (TTF) unit was prepared by the oxidative dimerization of 1,4‐bisdithiafulvenyl‐2,5‐didodecyloxybenzene using iodine. The polymer was soluble in common organic solvents such as CHCl₃ and toluene. The number‐average molecular weight of the polymer with dodecyloxy group was 24,900 determined from GPC. The UV–vis spectrum of the polymer showed the absorption maxima at 587, 712, and 803 nm, which are due to a cation radical of the vinylogous TTF unit in the polymer. The reduction of the polymer to its neutral state was performed using sodium hydrogen sulfite. The structure of the polymer was confirmed by ¹H NMR and UV–vis spectra compared with that of a dimer model compound prepared by oxidation of 1‐dithiafulvenyl‐2,5‐didodecyloxybenzene using iodine. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4600–4608, 2005     

On the Reaction of Thiazole‐2,4‐diamines with Isothiocyanates – Preparation and Transformation of 2,4‐Diaminothiazole‐5‐carbothioamides

In the reaction of thiazole‐2,4‐diamines 8 with isothiocyanates 1 , 2,4‐diaminothiazole‐5‐carbothioamides 9, 10, 18 , and 19 as well as thiazolo[4,5‐d]pyrimidine‐7(6H)‐thiones 21 were formed. The carbothioamides 9, 10 , and 18 were transformed by reaction with different types of monofunctional and bifunctional electrophiles into hitherto unknown acceptor‐substituted 4,4′‐([2,5′‐bithiazole]‐2′,4′‐diyl)bis[morpholines] 24 and 29 , the 2′,4′‐bis(dialkylamino)[2,5′‐bithiazol]‐4‐(5H)‐ones 30 , and the 4‐substituted 2′,4′‐bis(dialkylamino)‐2,5′‐bithiazoles 31 . From 30 and 31 new 4‐mono‐ or 4,5‐disubstituted 2′,4′‐bis(dialkylamino)‐2,5′‐bithiazoles 34, 35, 38 , and 39 as well as 5‐substituted 2′,4′‐bis(dialkylamino)[2,5′‐bithiazol]‐4(5H)‐ones 33, 36 , and 37 were prepared.     

New 7‐phosphanorbornenes derived from 2‐methyl‐1‐phenyl‐ and 1‐cyclohexyl‐3‐ methyl‐2,5‐dihydro‐1H‐phosphole 1‐oxides

Novel 7‐phosphanorbornene derivatives, such as 4, 5, 10 , and 11 were synthesized utilizing 1‐phenyl‐2‐methyl‐2,5‐dihydro‐1H‐phosphole oxide ( 1 ) and 1‐cyclohexyl‐3‐methyl‐2,5‐dihydro‐1H‐phosphole oxide ( 7 ) as the starting materials. Products 4 and 10 were prepared by trapping the corresponding phosphole oxide intermediates ( 3 and 9 , respectively) by N‐phenylmaleimide, while 5 and 11 were obtained by the dimerization of 3 and 9 , respectively. The trapping reaction was studied in details; on one hand, bromo‐2,3‐dihydro‐1H‐phosphole oxides ( 6‐1 and 6‐2 ) were pointed out as the intermediates, on the other hand, the trapping reaction was optimized. Bri‐ dged P‐heterocycles 4, 5, 10 , and 11 were tested in the fragmentation‐related phosphorylation of methanol. Hydrogenation of phosphanorbornenes 4 and 5 led to the corresponding phosphanorbornanes ( 12 and 14 , respectively) and to a reductive type of retro cycloaddition. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:320–326, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20097