58188-46-8Relevant academic research and scientific papers
Synthesis of calix[3]dipyrrins by a modified Lindsey protocol
Inoue, Mitsunori,Ikeda, Chusaku,Kawata, Yuji,Venkatraman, Sundararaman,Furukawa, Ko,Osuka, Atsuhiro
, p. 2306 - 2309 (2008/03/12)
(Figure Presented) Bowled over: Calix[3]dipyrrins were synthesized from pyrrole and aryl aldehyde precursors by the Lindsey protocol, modified by the presence of a small amount of water. These bowl-shaped macrocycles can accommodate three metal (M) ions such as NiII and CuII in a hexagonal M3O3 manner (see structure; Cu green, N blue, O red, C black).
Studies on cobalt(II), nickel(II) and copper(II) derivatives of some new meso-aryl substituted octabromoporphyrins
George, Regimol G.,Padmanabhan
, p. 679 - 684 (2008/10/09)
A series of Co(II), Ni(II) and Cu(II) derivatives of a variety of porphyrins with tolyl (H2TxTP) and naphthyl (H2NxTP) moieties as meso-substituents are synthesised and characterised. H 2TxTP has the tolyl functions bonded to meso-carbons at the o-, m- or p-positions of the tolyl moieties while H2NxTP has naphthyl groups bonded through their α- or β-positions. Their octabromo derivatives (MTxOBP and MNxOBP) were also synthesised by electrophilic substitution at the β-pyrrole positions. Optical spectra showed that the Q bands remain almost unaltered for both tolyl and naphthyl derivatives of the nonbrominated porphyrins while the B bands of their naphthyl derivatives are seen to be more red-shifted than their tolyl analogues. Even though a similar trend based on the meso-substituents is observed among all MTxOBP and MNxOBP derivatives, a substantial red-shift is seen for all the bromoderivatives compared to their nonbrominated species MTxTP and MNxTP. The energy difference Δν? associated with this red-shift of the Soret band is seen to be in the range 1700-2050 cm-1 for Co(II) and Ni(II) derivatives, the naphthyl derivatives always having higher values. Energy level reordering due to electron-withdrawing Br-substituents, distortion bringing about nonplanarity in the π-framework resulting in HOMO-LUMO level changes and the mesomeric effect due to meso-aryl moieties can be considered to be the reasons for the observed spectral changes. The EPR spectra of the Cu(II) derivatives of bromoporphyrins have lower A∥Cu and A⊥Cu hyperfine values compared to their nonbrominated analogues, indicating enhanced delocalisation of electron spin to the octabromoporphyrinato moiety. An enhanced Cu-N σ-covalency is seen in the Cu(II)-bromoporphyrins, as evident from their lower α2 values.
