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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.

Perylene diimides (PDIs) are among the most versatile and functional dyes for supramolecular structures displaying characteristic high absorptions and photo-luminescence properties as the prerequisite for optoelectronic thin film devices. Despite intense investigations into these semi-conducting and electro-active materials, details of their electronic structure are still under examination. In particular, non-planar twisted PDIs as an electron acceptor is a promising model system for efficient charge generation and transport processes. Therefore, a new dyad, an unsymmetrical PDI, N'-(2-ethylhexyl)-N'-(1,10-phenanthroline)-1,6,7,12-tetrakis-(4-methoxyphenoxy)-3,4,9,10-tetracarboxylic acid diimide (1) and its corresponding dichloroplatinum(ii) and dichloropalladium(ii) complexes as new dyads, [(Cl2)M(ii)-(1)] where, M(ii) = Pt(ii) (2) and Pd(ii) (3), were prepared. These dyads were fully characterized by FT-IR, 1D-NMR (1H-NMR and 13C-NMR), 2D-NMR (1H-1H COSY, 1H-13C HSQC, 1H-13C HMBC), MALDI TOF mass and UV-Vis spectroscopy. Electronic structure calculations have been employed based on Time-Dependent Density Functional Theory (TDDFT) calculations for the geometry-optimized electronic ground state structures in the gas phase and in dichloromethane (DCM). Current results indicate that 2 and 3 have similar HOMO-LUMO energy gaps which are smaller than 1. The energy and charge transfer processes with molecular structures are crucial for the design of future functional dyads based on donor and acceptor moieties for hybrid optoelectronic devices. Charge transfer mechanisms were also investigated with linear absorption, fluorescence and ultrafast transient absorption spectra for the newly synthesized compounds in DCM. The observed ultrafast intramolecular charge transfer from donor units on the PDI-2 compound is related to fluorescence quenching and faster singlet decay on transient measurements.

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 d 8 metal ions such as Pt(ii) and Pd(ii) having preferential square-planar geometry afforded the novel triads [(Cl 2 )M(ii)-(1)-M(ii)(Cl 2 )] 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 ( 1 H NMR and 13 C DEPT NMR), 2D-NMR ( 1 H- 1 H COSY, 1 H- 13 C HSQC, 1 H- 13 C 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.