Aggregation of slipped-cofacial phthalocyanine J-type dimers: Spectroscopic and AFM study

Heterogenous Preparations of Solution-Processable Cobalt Phthalocyanines for Carbon Dioxide Reduction Electrocatalysis

The development and implementation of technology that can capture and transform carbon dioxide (CO2) is of ongoing interest. To that end, the integration of molecular electrocatalysts into devices is appealing because of the desirable features of molecules, such as the ability to modify active sites. Here, we explore how the identity of the aliphatic group in 1,4,8,11,15,18,22,25-octaalkoxyphthalocyanine cobalt(II) affects the catalytic behavior for heterogeneous CO2 reduction electrocatalysis. The alkyl R-groups correspond to n-butoxy, sec-butoxy, and 2-ethylhexoxy. All of the catalysts are soluble in organic solvents and are readily solution-processed. However, the larger 2-ethylhexoxy group showed solution aggregation behavior at concentrations ≥1 mM, and it was, in general, an inferior catalyst. The other two catalysts show comparable maximum currents, but the octa sec-butoxy-bearing catalyst showed larger CO2 reduction rate constants based on foot-of-the-wave analyses. This behavior is hypothesized to be due to the ability of the sec-butoxy groups to eliminate the ability of the alkoxy oxygen to block Co Sites via ligation. CO2 reduction activity is rationalized based on solid-state structures. Cobalt(II) phthalocyanine and its derivatives are known to be good CO2 reduction catalysts, but the results from this work suggest that straightforward incorporation of bulky groups can improve the processability and per site activity by discouraging aggregation.

A New Way to Predict the Efficiency of Optical Limiters without Providing an Experiment: Processing of TDDFT Calculations for the Case of Pure Two-Photon Absorption

Laser-power-limiting devices play a predominant role in photonics because of their potential for protecting human eyes and optical devices that are sensitive to intense laser beams. This paper describes a new methodology for predicting the efficiency of optical limiting based on electric-field-induced changes in absorption spectra calculated with the TDDFT quantum-chemical method. Analytical equations are derived to evaluate the optical thresholds and speed of switching on, the dynamic range, and the degree of nonlinear attenuation of the radiation fluxes for the case of two-photon absorption. Thus, the researcher does not need to conduct costly experiments to evaluate the suitability of nonlinear absorbers for the creation of optical limiters. The possibility of developing a forecasting model is demonstrated by an example of a series of stable slipped-cofacial phthalocyanine J-type dimers, which were synthesized and investigated previously.

Synthesis and Spectroscopic and Luminescent Properties of Er, Yb and Lu Complexes with Cyano-Substituted Phthalocyanine Ligands

Based on 4,4′-[1,3/4-phenilenebis(oxy)]phthalodinitriles, the mixture of phthalocyaninates of various structures with rare-earth metals were obtained by template fusion method minimizing the side polymerization processes. Target monophthalocyaninates were isolated from the reaction mixture and purified using column and then gel permeation chromatography. The compounds were characterized by NMR, IR spectroscopy, mass spectrometry, and elemental analysis. The spectral properties were studied and the aggregation behavior of the synthesized Er, Yb, and Lu phthalocyaninates in chloroform, acetone, and tetrahydrofuran was determined. It has been shown that lutetium complexes with 3,4-dicyanophenoxyphenoxy ligands are the least stable and least resistant to aggregation in solution, while erbium and ytterbium phthalocyaninates proved to be stable in all studied media. The quantum yields and fluorescence lifetimes of the complexes in chloroform and tetrahydrofuran were calculated.

A3B type unsymmetrical and amphiphilic phthalocyanines: Synthesis, characterization, thermal stability and aggregation studies

This study reports the preparation, analysis, aggregation statuses and thermal properties of five phthalocyanines. The preparation of all molecules includes two steps: the first step is the preparation of phthalocyanine precursor molecules (A and B coded phthalonitriles); the second step is the synthesis of one metal-free and four metalled phthalocyanines (A₃B-Co, A₃B-Cu, A₃B-H, A₃B-Ni, and A₃B-Zn coded compounds). Compound A holds a hydrophobic chain (cetyl alcohol); compound B holds a hydrophilic chain (tetraethylene glycol). Phthalocyanines include three hydrophobic chains and one hydrophilic chain (A₃B type phthalocyanine). Characterization methods which were used to determine the structure of these compounds are Fourier Transform Infrared (FTIR), Proton Nuclear Magnetic Resonance (¹H NMR), Carbon-13 Nuclear Magnetic Resonance (¹³C NMR), and Ultraviolet Visible (UV Vis) spectroscopies and elemental analysis. The phthalocyanines have high stability up to 260 °C as a minimum value. Aggregation statuses of the phthalocyanines change to the metal from the metal or to the solvent from the solvent.