A novel AB3-type trimeric zinc(II)-phthalocyanine as an electrochromic and optical limiting material.

Recent advances in the practical applications of metallophthalocyanines (MPcs) in different technological fields have stimulated us to design and synthesize a new asymmetric AB3-type trimeric zinc(ii)-phthalocyanine (1). This bulky and high molecular weight compound was characterized by elemental analysis, 1H, 13C DEPT, and 1H-1H NOESY NMR, HR MALDI-TOF mass spectrometry, UV-vis, and FT-IR (ATR) techniques. In-depth electrochemical studies show that 1 displays quasi-reversible three one-electron reductions and two one- or two-electron oxidation processes, rather than any redox processes including the transfer of three-electrons in one-step. Besides this, in situ spectroelectrochemical measurements suggest the good application potential of 1 as an electrochromic material in display technologies. A study of the nonlinear optical properties (NLOs) of 1 reveals that the poly(methylmethacrylate) (PMMA) composite film displays a much larger nonlinear absorption coefficient and a lower saturable absorption threshold for optical limiting when compared to the same Pc molecules in solution. Ultrafast transient absorption measurements reveal the intersystem crossing mechanism. Density functional theory (DFT) was used for the geometry optimizations and time dependent-DFT (TD-DFT) for HOMO/LUMO energies and electronic transitions for 1.

Spectroscopic, electrochemical and photovoltaic properties of Pt(ii) and Pd(ii) complexes of a chelating 1,10-phenanthroline appended perylene diimide.

In this study, a bis-chelating bridging perylene diimide ditopic ligand, namely N,N'-di(1,10-phenanthroline)-1,6,7,12-tetrakis-(4-methoxyphenoxy)perylene tetracarboxylic acid diimide (1), was synthesized and characterized. Further reactions of 1 with d8 metal ions such as Pt(ii) and Pd(ii) having preferential square-planar geometry afforded the novel triads [(Cl2)M(ii)-(1)-M(ii)(Cl2)] where M(ii) = Pt(ii) (2), and Pd(ii) (3), respectively. The isolated triads and the key precursor were fully characterized by FT-IR, 1D-NMR (1H NMR and 13C DEPT NMR), 2D-NMR (1H-1H COSY, 1H-13C HSQC, 1H-13C HMBC), MALDI-TOF mass and UV/Vis spectroscopy. The electrochemical properties of 1, 2 and 3 were investigated by cyclic voltammetry as well as in situ spectroelectrochemistry and also in situ electrocolorimetric measurements. These compounds were shown to exhibit net colour changes suitable for electrochromic applications. The compounds exhibited remarkably narrow HOMO-LUMO gaps, leading to their ease of reduction at low negative potentials. More importantly, dye-sensitized solar cells (DSSCs) were also fabricated using 1-3 to clarify the potential use of these complexes as a sensitizer. Analysis of the experimental data indicated that 2 has good potential as a sensitizer material for DSSCs.

Gas sensing and electrochemical properties of tetra and octa 2H-chromen-2-one substituted iron(II) phthalocyanines.

The synthesis of novel alpha tetra, beta tetra and beta octa 4-(4-methoxyphenyl)-8-methyl-coumarin-7-oxy, and beta octa 4-chloro-5-(4-(4-methoxyphenyl)-8-methylcoumarin-7-oxy) substituted iron(II) phthalocyanines has been achieved by the reaction of the corresponding phthalonitriles with iron(II) acetate. The compounds were characterized by elemental analysis, FT-IR, UV-vis, and MALDI-TOF mass spectrometry. The reduction and oxidation properties of the compounds were identified by voltammetric and in situ spectroelectrochemical measurements. The gas sensing behavior of the spin coated films of the differently substituted iron(II) complexes towards CO2, CO and SO2 was investigated at various temperatures between 300 K and 500 K. While exposure to SO2 had no considerable influence on the sensor current, the presence of CO and CO2 gases led to a large increase in sensor currents. The effect of relative humidity on the CO and CO2 sensing capability of the spin coated films was also studied. The results showed that the presence of water vapor, acting as an interference gas, causes a decrease in the CO2 sensitivity, but an increase in the CO sensitivity of the sensors. The experimental adsorption data were analyzed using the Elovich kinetic model. Linear regression analysis results show that the Elovich equation provides the best correlation for the CO2 and CO adsorption processes under humid conditions. However, the experimental data deviated considerably from the theoretical model under a dry atmosphere.