A series of 4,4＇-disubstituted-[2,2＇]-bipyridines, featuring electron withdrawing/donating functional groups such as amino, chloro, nitro, ethoxycarbonyl, carboxy, methyl, methoxy and hydroxymethyl, have been syn- t...A series of 4,4＇-disubstituted-[2,2＇]-bipyridines, featuring electron withdrawing/donating functional groups such as amino, chloro, nitro, ethoxycarbonyl, carboxy, methyl, methoxy and hydroxymethyl, have been syn- thesized and employed in the copolymerization of carbon monoxide （CO） and styrene. The available bipyridine and its derivatives were coordinated with palladium （ II ） acetate for catalyzing the copolymerization of CO and styrene, and the concomitant polyketone was characterized by means of t3C NMR, FTIR, differential scanning calo- rimetry （DSC） and element analysis techniques concerning its structure and thermal performance. The effect of dif- ferent electron-donating and electron-withdrawing groups on catalyst performance and molecular weight of co- polymer was studied under certain experimental condition. It has been proved that the enhancement of electron donating and conjugative effects on bipyridine ligand will not only improve the catalytic activity of the composi- tion, but also increase the molecular weight of the as-prepared polyketone. The catalytic activity is the highest in hydroxymethyl substituted 2,2＇-bipyridine ligand（l 356 gSTCO/（gPd · h））, when the molecular weight and polydispersity index of the polyketone are Mn = 8 502, Mw = 1 3440 and Mw/Mn = 1.581, respectively.展开更多
Twenty five samples of 4,4'-disubstituted stilbene derivatives were synthesized, and their UV absorption max wavelengths were determined in over 10 kinds of solvents including cyclohexane, ether, chloroform, aceto...Twenty five samples of 4,4'-disubstituted stilbene derivatives were synthesized, and their UV absorption max wavelengths were determined in over 10 kinds of solvents including cyclohexane, ether, chloroform, acetonitrile and ethanol, in which 242 experimental data were recorded. The effects of substituents and solvents on the energy of their UV absorption max wavelengths were discussed. The research results showed: the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes was mainly affected by their intramolecular structure (substituent effect) in a given solvent, that is, the energy is dominated by both of excited-state substituent parameter o-~c and polar substituent constant crp. While their energy was dominated by the substituent effect and solvent effect in different kinds of solvents. An equation quantifying the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes was developed. In addition, it is found that the n-octanol/water partition coefficient (logP) is more effective than the solvatochromic dye (ET(30)) in scaling the solvent effect. The equation employed the parameter logP has a better correlation and more specific physical meaning. Further, the energies of UV absorption max wavelengths of some reported compounds were predicted by the obtained equation, which are in agreement with their experimental values.展开更多
基金Supported by Tianjin Natural Science Foundation(No.07JCYBJC00600)
文摘A series of 4,4＇-disubstituted-[2,2＇]-bipyridines, featuring electron withdrawing/donating functional groups such as amino, chloro, nitro, ethoxycarbonyl, carboxy, methyl, methoxy and hydroxymethyl, have been syn- thesized and employed in the copolymerization of carbon monoxide （CO） and styrene. The available bipyridine and its derivatives were coordinated with palladium （ II ） acetate for catalyzing the copolymerization of CO and styrene, and the concomitant polyketone was characterized by means of t3C NMR, FTIR, differential scanning calo- rimetry （DSC） and element analysis techniques concerning its structure and thermal performance. The effect of dif- ferent electron-donating and electron-withdrawing groups on catalyst performance and molecular weight of co- polymer was studied under certain experimental condition. It has been proved that the enhancement of electron donating and conjugative effects on bipyridine ligand will not only improve the catalytic activity of the composi- tion, but also increase the molecular weight of the as-prepared polyketone. The catalytic activity is the highest in hydroxymethyl substituted 2,2＇-bipyridine ligand（l 356 gSTCO/（gPd · h））, when the molecular weight and polydispersity index of the polyketone are Mn = 8 502, Mw = 1 3440 and Mw/Mn = 1.581, respectively.
基金financially supported by the National Natural Science Foundation of China (21072053 & 20772028) the Scientific Research Fund of Hunan Provincial Education Department (10K025)
文摘Twenty five samples of 4,4'-disubstituted stilbene derivatives were synthesized, and their UV absorption max wavelengths were determined in over 10 kinds of solvents including cyclohexane, ether, chloroform, acetonitrile and ethanol, in which 242 experimental data were recorded. The effects of substituents and solvents on the energy of their UV absorption max wavelengths were discussed. The research results showed: the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes was mainly affected by their intramolecular structure (substituent effect) in a given solvent, that is, the energy is dominated by both of excited-state substituent parameter o-~c and polar substituent constant crp. While their energy was dominated by the substituent effect and solvent effect in different kinds of solvents. An equation quantifying the energy of UV absorption max wavelengths of 4,4'-disubstituted stilbenes was developed. In addition, it is found that the n-octanol/water partition coefficient (logP) is more effective than the solvatochromic dye (ET(30)) in scaling the solvent effect. The equation employed the parameter logP has a better correlation and more specific physical meaning. Further, the energies of UV absorption max wavelengths of some reported compounds were predicted by the obtained equation, which are in agreement with their experimental values.
