291780-69-3Relevant academic research and scientific papers
Experimental and theoretical characterization of 5,10- diminoporphodimethenes: Dearomatized porphyrinoids from palladium-catalyzed hydrazinations of 5,10-diarylporphyrins
Basic, Bruno,Locos, Oliver B.,Rintoul, Llew,Kan, Jinglan,Jiang, Jianzhuang,Arnold, Dennis P.
, p. 813 - 824 (2014/07/08)
A new dearomatized porphyrinoid, 5,10-diiminoporphodimethene (5,10-DIPD), has been prepared by palladium-catalyzed hydrazination of 5,10-dibromo-15,20- bis(3,5-di-tert-butylphenyl)porphyrin and its nickel(II) complex, by using ethyl and 4-methoxybenzyl carbazates. The oxidative dearomatization of the porphyrin ring occurs in high yield. Further oxidation with 2,3-dichloro-5,6- dicyanobenzoquinone forms the corresponding 5,10-bis(azocarboxylates), thereby restoring the porphyrin aromaticity. The UV/visible spectra of the Ni II DIPDs exhibit remarkable redshifts of the lowest-energy bands to 780 nm, and differential pulse voltammetry reveals a contracted electrochemical HOMO-LUMO gap of 1.44 V. Density functional theory (DFT) was used to calculate the optimized geometries and frontier molecular orbitals of model 5,10-DIPD Ni7c and 5,10-bis(azocarboxylate) Ni8c. The conformations of the carbamate groups and the configurations of the C=N-Z unit were considered in conjunction with the NOESY spectra, to generate the global minimum geometry and two other structures with slightly higher energies. In the absence of solution data regarding conformations, ten possible local minimum conformations were considered for Ni8c. Partition of the porphyrin macrocycle into tri- and monopyrrole fragments in Ni7c and the inclusion of terminal conjugating functional groups generate unique frontier molecular orbital distributions and a HOMO-LUMO transition with a strong element of charge transfer from the monopyrrole ring. Time-dependent DFT calculations were performed for the three lowest-energy structures of Ni7c and Ni8c, and weighting according to their energies allowed the prediction of the electronic spectra. The calculations reproduce the lower-energy regions of the spectra and the overall forms of the spectra with high accuracy, but agreement is not as good in the Soret region below 450 nm. A new dearomatized porphyrinoid, 5,10-diiminoporphodimethene, has been prepared and characterized spectroscopically and by theoretical calculations (see figure). The strongly redshifted HOMO-LUMO absorption band has the character of a charge transfer from the unique pyrrole ring to the tripyrrole fragment. Copyright
A porphyrin square: Synthesis of a square-shaped π-conjugated porphyrin tetramer connected by diacetylene linkages
Sugiura, Ken-Ichi,Fujimoto, Yoshinobu,Sakata, Yoshiteru
, p. 1105 - 1106 (2007/10/03)
A square-shaped π-conjugated porphyrin tetramer has prepared: the excitation energies of both the Soret and Q bands, 19 880 (503) and 15 180 cm-1 (659 nm), respectively, are quite low compared with those for the monomer and reported cyclic porphyrin oligomers.
