Synthesis and characterization of some heteroleptic copper(II) complexes based on meso-substituted dipyrrins

Investigation of copper oxidation states in plasmonic nanomaterials by XAS and Raman spectroscopy

A shell-isolated nanoparticle enhanced surface Raman technique and XANES for detection of copper(ii) or copper(i) plasmonic-nanocatalysts.

Quantifying Triplet State Formation in Zinc Dipyrrin Complexes

Photocatalysis is a promising method to harness solar energy and use it to form fuels and other high-value chemicals, but most sensitizers used in photocatalytic reactions are complexes of rare and expensive metals such as ruthenium and iridium. Zinc dipyrromethene complexes have potential to be a more earth-abundant alternative, but their photophysical properties are largely unexplored. In this study, triplet state formation was quantified in two zinc dipyrromethene complexes, with and without heavy atoms, by transient absorption spectroscopy. Without heavy atoms, the triplet quantum yield was 16% in toluene and 27% in THF. With the addition of heavy I atoms, the triplet quantum yield increased to 62-63% and was insensitive to solvent polarity. The fact that in the absence of heavy atoms the triplet yield is affected by solvent polarity and in the presence of heavy atoms it is not suggests that triplet formation occurs through different pathways in the two complexes. These triplet yields meet or exceed those of successful organic photosensitizers, illustrating the potential for zinc dipyrromethene complexes as photosensitizers.

Spacer length dependent architectural diversity in bis-dipyrrin copper(ii) complexes

A series of copper(ii) complexes (1-9 and 3') derived from bis-dipyrrin ligands (L1-L9 and L3') with diverse spacer lengths [-(CH₂)_n-] have been described. Structural diversities in these complexes have been explicitly established by spectral and structural studies on these and a closely related nickel(ii) complex (3''). All the ligands and complexes have been thoroughly characterized by spectroscopic studies (ESI-MS, IR, ¹H, ¹³C NMR, UV/vis) and structures of 2, 3', 3'', 6, 8 and 9 were determined by X-ray single crystal analyses. It has been unambiguously established that ligands with n ≤ 6 gave heteroleptic binuclear (1-5), while those with n ≥ 7 yielded homoleptic mononuclear (6-9) bis-dipyrrinato complexes. Spectral and structural studies revealed distorted square planar (1-5) and distorted tetrahedral geometries (6-9) about the copper(ii) centre in these complexes which has further been evidenced by EPR and electrochemical studies. Structural differences based on the odd and even number of methylene spacers in these complexes have been supported by DFT studies. A line between the syn- and anti-conformations of the complexes has been drawn on the basis of a limiting spacer length.