A simple, novel and convenient method for the synthesis of 1-aminophosphinic acids: synthesis of a novel C2-symmetric phosphinic acid pseudodipeptide

Synthesis of Novel Symmetric Porphyrin Schiff Base Dimers by Solid–Liquid Reaction Methodology

“…On the other hand, the reaction between one equivalent of meta or para-phenylenediamine and an excess of TIPPCHO, NiTIPPCHO, or CuTIPPCHO produced porphyrin/metalloporphyrin dimer (17), (18), (19), (20), (21), or (22) (Table 4). TLC was used to monitor the reaction progress.…”

“…After 6 h of reflux, reaction mixture was cooled down at the room temperature. The alumina powder was filtered out from the reaction mixture, and the porphyrin/metalloporphyrin dimer (17), (18), (19), (20), (21), or (22) was isolated from the surface of alumina by washing with carbon tetrachloride…”

“…Hence, by controlling the molar concentration of the reactants, type of the product can be controlled. The yields of the dimer (17), (18), (19), (20), (21), and (22) after purification by column chromatography and recrystallization are listed in Table 4. The comparison of electronic absorption spectra of amino Schiff base (11), (12), (13), (14), (15), and (16) with their corresponding dimer (17), (18), (19), (20), (21), and (22) revealed 8-15 nm red shift in their Soret bands along with significant broadening (Fig.…”

“…1). Dimer (19) and (22) also exhibited extra absorptions at 605 and 598 nm, respectively. These changes indicate some degree of electronic perturbation has occurred upon dimerization.…”

“…The stretching of formyl group in metalloporphyrin (7), (8), (9), or (10) was observed around 1669-1678 cm À1 . The disappearance of N-H vibration around 3345-3450 cm À1 and appearance of Schiff base (11), (12), (13), (14), (15), or (16) revealed two absorption bands around 3345-3450 cm À1 due to the N-H stretching of -NH 2 , which were absent in the dimer (17), (18), (19), (20), (21), or (22). 1 H NMR spectrum of Schiff base (11), (12), (14), or (15) displayed a slightly broad singlet between 4.09-4.21 δ accounting for the -NH 2 group that disappeared after condensation with TIPPCHO, NiTIPPCHO, or CuTIPPCHO.…”