HeI ultraviolet photoelectron spectra of some thienyl polyethylenic dimethyl malonates compoundsf(1),(2),(3)(to see Fig.1)have been given in this paper. The assignment of the spectra are also done using the optimized ...HeI ultraviolet photoelectron spectra of some thienyl polyethylenic dimethyl malonates compoundsf(1),(2),(3)(to see Fig.1)have been given in this paper. The assignment of the spectra are also done using the optimized MNDO molecular orbital calculation for each studied molecules. It is shown that the linear reduction of HOMO ionization energy (Ip) which is mainly antiboding in character of ethylenic group with the increment of ethylenic group number is fortunately the basis of the homologous lineax rule of this series of compounds. And it is also pointed out that weight of two -COOCH3 groups in the HoMO orbital is very small, that is to say, they can not be differentiated as the terminal or substituent.展开更多
Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano and carboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts...Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano and carboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts for the methyl-, methylene- and beta-protons havebeen found to conform very well to the rule of homologous linearity. The mass spectra forthe α-cyano polyenic ester series show strong peaks for the fragments of M-COOEt but noneof M-CN, indicating that the CN group seems to be in stronger conjugation with the poly-enic chain than the COOEt group does. In all the forked series studided, a red shift in electronic spectra is brought about upon the introduction of an electron-attractive branching group, just like the case of introducing an electron-repelling substituent. This has been taken as an indication of the predominance of themolecular integrality over the group characteristics. By means of the method of similar triangles between a homologous line for a linearseries and that for the corresponding forked compounds, the equivalent △Ns for a branching group may be calculated with accuracy. Based on the value of this equivalent, the substituentnature of the structural effect of the branching group has been inferred. The electronic absorption maxima for four series of the forked compounds have been cal-culated by means of the extended homologous equation for the corresponding linear compounds.With an appropriate correction for the positional effect of the substituent equivalent, the cal-culated wavelengths agree generally with experimental data within ± 7nm.展开更多
I. INTRODUCTIONIn the preceding paper we have reported that in a forked conjugative thienylpolyenic system with two electron-attracting groups at one end, the structural
It is demonstrated quantitatively that the serial number N is not m + n + 4 in the nitrogen bridge conjugated system (Ⅸ), so the lone pair of electrons on the nitrogen cannot conjugate with acenyl branch and formyl p...It is demonstrated quantitatively that the serial number N is not m + n + 4 in the nitrogen bridge conjugated system (Ⅸ), so the lone pair of electrons on the nitrogen cannot conjugate with acenyl branch and formyl polyenic branch simultaneously. The character of UV spectra and substituent equivalents (△Ns) show that acenyl branch competes for the lone pair of electrons with formyl polyenic branch. If the length m of acenyl branch is lengthened while n keeps constant, a point where the acenyl branch is predominant over formyl polyenic branch in competition, will eventually be reached. On the other hand, the effect of the latter will become greater than the former. The effect of the two branches predominates each other alternately with the alternate increase in m and n values.展开更多
1 Introduction It has been known from the experiment that two conjugated systems of aromaticheterocyclic carbonyl and phenyl carbonyl groups in the aromatic heterocylic phenylketone compounds are not equivalent and so...1 Introduction It has been known from the experiment that two conjugated systems of aromaticheterocyclic carbonyl and phenyl carbonyl groups in the aromatic heterocylic phenylketone compounds are not equivalent and so are not coplanary. The synhesis展开更多
In this paper, the following carbonyl-imino bridged compounds and related analogs havebeen synthesized:X= C1, m = 0); and the structural effect of the carbonyl-imino bridges has been studied by means of the UV and oth...In this paper, the following carbonyl-imino bridged compounds and related analogs havebeen synthesized:X= C1, m = 0); and the structural effect of the carbonyl-imino bridges has been studied by means of the UV and other properties of the compounds. A new conception of conjugative segment is put forward. The structural bases for each of the three π-π* bands of (C) are ascertained and verified by modification on structure of segments, such as eliminating, merging, lengthening or shortening of segments. It is demonstrated that both bridges -CO-and -NH- can block the conjugated polarization of the whole molecule so as to form three segments S, M and L of which the λmax each exhibits relative independence. The electronic absorption peaks resulting from different segments can be readily recognized and the existence of each segment can be ascertained. This may provide a new way for structural analysis of bridged compounds.展开更多
文摘HeI ultraviolet photoelectron spectra of some thienyl polyethylenic dimethyl malonates compoundsf(1),(2),(3)(to see Fig.1)have been given in this paper. The assignment of the spectra are also done using the optimized MNDO molecular orbital calculation for each studied molecules. It is shown that the linear reduction of HOMO ionization energy (Ip) which is mainly antiboding in character of ethylenic group with the increment of ethylenic group number is fortunately the basis of the homologous lineax rule of this series of compounds. And it is also pointed out that weight of two -COOCH3 groups in the HoMO orbital is very small, that is to say, they can not be differentiated as the terminal or substituent.
文摘Five homologous series of bifurcate systems of aliphatic and aromatic polyenic cyano and carboxylic compounds have been prepared and studied. The electronic absorption spectra forthe series and the NMR chemical shifts for the methyl-, methylene- and beta-protons havebeen found to conform very well to the rule of homologous linearity. The mass spectra forthe α-cyano polyenic ester series show strong peaks for the fragments of M-COOEt but noneof M-CN, indicating that the CN group seems to be in stronger conjugation with the poly-enic chain than the COOEt group does. In all the forked series studided, a red shift in electronic spectra is brought about upon the introduction of an electron-attractive branching group, just like the case of introducing an electron-repelling substituent. This has been taken as an indication of the predominance of themolecular integrality over the group characteristics. By means of the method of similar triangles between a homologous line for a linearseries and that for the corresponding forked compounds, the equivalent △Ns for a branching group may be calculated with accuracy. Based on the value of this equivalent, the substituentnature of the structural effect of the branching group has been inferred. The electronic absorption maxima for four series of the forked compounds have been cal-culated by means of the extended homologous equation for the corresponding linear compounds.With an appropriate correction for the positional effect of the substituent equivalent, the cal-culated wavelengths agree generally with experimental data within ± 7nm.
文摘I. INTRODUCTIONIn the preceding paper we have reported that in a forked conjugative thienylpolyenic system with two electron-attracting groups at one end, the structural
基金Project supported by the National Natural Science Foundstion of China.
文摘It is demonstrated quantitatively that the serial number N is not m + n + 4 in the nitrogen bridge conjugated system (Ⅸ), so the lone pair of electrons on the nitrogen cannot conjugate with acenyl branch and formyl polyenic branch simultaneously. The character of UV spectra and substituent equivalents (△Ns) show that acenyl branch competes for the lone pair of electrons with formyl polyenic branch. If the length m of acenyl branch is lengthened while n keeps constant, a point where the acenyl branch is predominant over formyl polyenic branch in competition, will eventually be reached. On the other hand, the effect of the latter will become greater than the former. The effect of the two branches predominates each other alternately with the alternate increase in m and n values.
文摘1 Introduction It has been known from the experiment that two conjugated systems of aromaticheterocyclic carbonyl and phenyl carbonyl groups in the aromatic heterocylic phenylketone compounds are not equivalent and so are not coplanary. The synhesis
基金Project supported by the National Natural Science Foundation of China.
文摘In this paper, the following carbonyl-imino bridged compounds and related analogs havebeen synthesized:X= C1, m = 0); and the structural effect of the carbonyl-imino bridges has been studied by means of the UV and other properties of the compounds. A new conception of conjugative segment is put forward. The structural bases for each of the three π-π* bands of (C) are ascertained and verified by modification on structure of segments, such as eliminating, merging, lengthening or shortening of segments. It is demonstrated that both bridges -CO-and -NH- can block the conjugated polarization of the whole molecule so as to form three segments S, M and L of which the λmax each exhibits relative independence. The electronic absorption peaks resulting from different segments can be readily recognized and the existence of each segment can be ascertained. This may provide a new way for structural analysis of bridged compounds.
