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This study focused on preparation of stable polymer films of NiII‐ and CoII‐tetraaminophthalocyanines, p‐NiTAPc and p‐CoTAPc, respectively, for highly efficient heterogeneous electrochemical carbon dioxide (CO2) reduction in a flow electrolysis cell. Major development represented in this work was fabrication of p‐NiTAPc and p‐CoTAPc films via electropolymerization of their corresponding monomers on carbon‐based substrates without using binder or conducting additive materials to obtain efficient gas diffusion electrodes (GDEs) for scalable, productive and selective CO2‐to‐CO conversion. The target polymers were characterized by UV‐visible spectrophotometry, attenuated total reflection‐Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectroscopy and cyclic voltammetry. According to controlled potential electrolysis and gas chromatography, p‐NiTAPc‐catalyzed CO2 reduction at −0.99 V vs. reversible hydrogen electrode (RHE) gave 953 mL of CO in a period of 16 hours with current density and Faradaic efficiency (FE) of 109±1 mA ⋅ cm−2 and 99±2 %, respectively. A p‐CoTAPc‐modified GDE exhibited superior catalytic performance to the case of p‐NiTAPc in terms of catalyst stability and CO productivity by performing the continuous CO2 reduction at the potential of −1.10 V vs. RHE for up to 41 hours and affording almost 3 times higher amount of CO with the current density of 161±5 mA⋅cm–2 and 95±2 % FE. [ABSTRACT FROM AUTHOR]

In this work, new hybrid catalysts based on molecularly dispersed nickel complexes on N-doped graphene were developed for electrochemical CO2 reduction (ECR). Nickel(II) complexes (1-Ni, 2-Ni), and a new crystal structure ([2-Ni]Me), featuring N4-Schiff base macrocycles, were synthesized and investigated for their potential in ECR. Cyclic voltammetry (CV) in NBu4PF6/CH3CN solution demonstrated that the nickel complexes bearing N–H groups (1-Ni and 2-Ni) showed a substantial current enhancement in the presence of CO2, while the absence of N–H groups ([2-Ni]Me) resulted in an almost unchanged voltammogram. This indicated the necessity of the N–H functionality towards ECR in aprotic media. All three nickel complexes were successfully immobilized on nitrogen-doped graphene (NG) via non-covalent interactions. All three Ni@NG catalysts exhibited satisfactory CO2-to-CO reduction in aqueous NaHCO3 solution with the faradaic efficiency (FE) of 60–80% at the overpotential of 0.56 V vs. RHE. The ECR activity of [2-Ni]Me@NG also suggested that the N–H moiety from the ligand is less important in the heterogeneous aqueous system owing to viable hydrogen-bond formation and proton donors from water and bicarbonate ions. This finding could pave the way for understanding the effects of modifying the ligand framework at the N–H position toward fine tuning the reactivity of hybrid catalysts through molecular-level modulation. [ABSTRACT FROM AUTHOR]

The synthesis of a set of porphyrin dyads bearing hydrocarbon tethers that include an ethnyl group and a triallyl group is described. Results reveal that the molecular footprint of the former dyads is similar to that of a monomer while that of the latter dyads is larger.

The synthesis of porphyrinic macrocycles and related compounds requires the ability to carry out reactions at the pyrrolic alpha and alpha'-positions. Under mild reaction conditions, the 2-alkylthio group is readily removed as required for elaboration of porphyrinic precursors.

Boron-dipyrrin chromophores containing a 5-aryl group with or without internal steric hindrance toward aryl rotation was synthesized and then characterized via X-ray diffraction, static and time-resolved optical spectroscopy, and theory. It is revealed that the critical role of aryl-ring rotation in governing the excited state dynamics and fluorescence properties of the dyes and the result should facilitate the further use of these class of dyes and related systems as optical probes in the life science.

The synthesis of a number of porphyrins that can be used for the study of the interplay of molecular design and charge-storage properties is described. Each porphyrin bears a formyl group distal to the surface attachment group for subsequent derivatization with a molecular entity that comprises the electrolyte.

The synthesis of linear multiporphyrin arrays (triads, tetrad, pentad) bearing solubilizing 7-tridecyl (swallowtail) groups is presented. The rodlike arrays are composed of zinc porphyrins at the termini and 1,2, or 3 free base porphyrins at the core.

Porphyrin building blocks bearing 1-4 swallowtail groups were obtained by studying synthetic routes. The swallowtail substituents do not alter the electronic or photophysical properties of the porphyrins, making them apt as building blocks for constructing large arrays for detailed physicochemical studies.

This research presents a new series of tetrabenzoporphyrins (TBPs) bearing p‐diphenylaminophenylethynyl and p‐carboxylphenylethynyl groups or two p‐carboxylphenylethynyl groups in a trans‐fashion on a TBP core for photoelectrochemical O2 reduction. Impact of electron‐donating diphenylamino and electron‐withdrawing surface‐anchoring carboxyl groups on photophysical and electrochemical properties of the target TBPs was experimentally and theoretically investigated in comparison with those of their benchmark analog. The results show that while the p‐carboxylphenylethynyl group give an electronic contribution to the molecules by lowering energy gap, the role of the p‐diphenylaminophenylethynyl group is found to be trivial. Preliminary investigation on electrochemical O2 reduction indicates significant catalytic activities of TBP‐modified TiO2/fluorene‐doped tin oxide electrodes at potentials of −0.2 V and −0.3 V vs. normal hydrogen electrode (NHE) in a pH‐neutral and ambient aqueous condition, leading to H2O2 formation. Upon photoirradiation, catalytic performance of such TBP‐based electrodes is further enhanced with the optimum yield obtained when the dicarboxyl derivatives and the potential of −0.3 V vs. NHE are applied. Proposed photoinjection mechanism of the dye/TiO2 simulated by time‐dependent density functional theory calculations supported the experimental results indicating the favorable role of the target TBPs as photoelectrocatalysts in the O2 reduction. [ABSTRACT FROM AUTHOR]

A p-diphenylethyne-linked zinc porphyrin dyad with two [super 13]C atoms and one unlabeled was prepared to understand ground-state hole/electron-transfer process in oxidized multiporphyrin architectures. The slower hole-transfer rate compared to that of meso-diphenylethyne-linked, electron-rich porphyrin dyads is attributed to the [a.sub.2u] HOMO with substantial electron/spin density at the meso-carbons.

A new strategy for preparing porphyrins that bear up to four different meso-substituents (ABCD-porphyrins) is reported. The reaction is based on synthesis of 1-protected 19-acylbilane by acid-catalyzed condensation at high concentration.

The investigation of the ground-state electronic communication in diphenylethyne-linked zinc-porphyrin dyads was observed to be fast on the time scale of the [super 13]C hyperfine clock.

Three sets of zinc porphyrins (22 altogether) are prepared in order to identify suitable chemistry that enables in situ stepwise synthesis of covalently linked architectures on an electroactive surface. The overall results have shown the ability to prepare covalently linked constructs on a surface without protecting groups in a stepwise manner bodes well for the systematic preparation of a wide variety of functional molecular devices.