Azines of porphyrinoids. Does azine provide conjugation between chromophores?

Modification of β-Octaethylporphyrin via Insertion of Amino and Azino Groups into meso-Positions

“…Upon insertion of the azine substituent into 5 a new intense band at 483 nm has emerged in 6 and the slight bathochromic shift of the Soret band for 11 nm and 16 nm shift of Q-bands were observed (Figure 2). Comparing spectra of 6 and similar azine derivative of NiOEP and p-nitrobenzaldehyde (NiOEPCHNNCHC 6 H 4 NO 2 ) [38] but without meso-amido substituent, one can see that the spectrum of 6 is bathochromically shifted relatively that of NiO-EPCHNNCHC 6 H 4 NO 2 , and Q-bands are of relatively higher intensity. These differences are due to the influence of mesotrifluoroacetamido group.…”

“…For comparison, the spectra of the p-bromobenzalazine derivative of methyl pyropheophorbide d (PPPdNNCHC 6 H 4 Br) and the azine bridged conjugate of NiOEP and PPPd(NiOEPCHNNPPPPd) were shown. [38] Spectra of all azines of PPPd contain broad Soret band which is resolved in two bands in the case of NiOEPCHNNPPPPd. The Soret band of the conjugate 9 is red-shifted for 23 nm compared to the NiOEPCHNNPPPPd which can be attributed to the influence of the meso-trifluoroacetamido substituent.…”

“…Previously, aryl azines of porphyrinoids have been synthesized by the condensation of tetrapyrrole hydrazones and arylaldehydes. [38] In turn, hydrazones have been obtained via formylation followed by the reaction of the formylporphyrins with hydrazine. [39] The trifluoroacylated amino derivative 5 was used as a starting material for the electron acceptor fragment insertion as the trifluoroacyl played a role of a protective group for the reactive amino group.…”

Direct C–H borylation of vinylporphyrins via copper catalysis

“…The substituents of the meso-ethenyl group do not affect the electron system of the porphyrin dye due to the absence of the π-conjugation of the perpendicularly rotated CvC double bond with the tetrapyrrole macrocycle. 35 Scheme 7 The Suzuki coupling of the borylated meso-vinylporphyrin (10) with aryliodides. However, the products of arylation of methyl pyropheophorbide-a (1a) demonstrate the bathochromic shift of the absorption bands (Fig.…”

Synthesis of β-Octaethylporphyrin Conjugates with Nitrogen and Sulfur Containing Heterocycles

“…[19] The porphyrin with aldehyde group, which is easily accessible by this way, is a versatile building block, [20] often used in diverse transformations inherent to the carbonyl group, [21] in particular, in oxidation, reduction, formation of oximes, semicarbazones, imines and cyanohydrins, condensation with CH-acids, Wittig reaction, as well as reactions with organometallic reagents. [22][23][24] Previously, we have reported on the functionalization of the porphyrins through the formylation, followed by the condensation with nitrogen nucleophiles, leading to insertion of imino, [25][26][27] hydrazono [19,28] and azino [29] groups into the meso-position of the tetrapyrrole macrocycle. In the framework of this work, the formylporphyrin was used in condensation reactions with CH-acids to obtain porphyrin conjugates with heterocycles.…”