Similar, Yet Different: Long-Range Metal-Metal Coupling and Electron-Transfer Processes in Metal-Free 5,10,15,20-Tetra(ruthenocenyl)porphyrin

The electronic structure, redox properties, and long-range metal-metal coupling in metal-free 5,10,15,20-tetra(ruthenocenyl)porphyrin (H₂TRcP) were probed by spectroscopic (NMR, UV-vis, magnetic circular dichroism (MCD), and atmospheric pressure chemical ionization (APCI)), electrochemical (cyclic voltammetry, CV, and differential pulse voltammetry, DPV), spectroelectrochemical, and chemical oxidation methods, as well as theoretical (density functional theory, DFT, and time-dependent DFT, TDDFT) approaches. It was demonstrated that the spectroscopic properties of H₂TRcP are significantly different from those in H₂TFcP (metal-free 5,10,15,20-tetra(ferrocenyl)porphyrin). Ruthenocenyl fragments in H₂TRcP have higher oxidation potentials than the ferrocene groups in the H₂TFcP complex. Similar to H₂TFcP, we were able to access and spectroscopically characterize the one- and two-electron oxidized mixed-valence states in the H₂TRcP system. DFT predicts that the porphyrin π-system stabilizes the [H₂TRcP]⁺ mixed-valence cation and prevents its dimerization, which is characteristic for ruthenocenyl systems. However, formation of the mixed-valence [H₂TRcP]²⁺ is significantly less reproducible than the formation of [H₂TRcP]⁺. DFT and TDDFT calculations suggest the ruthenocenyl fragment dominance in the highest occupied molecular orbital (HOMO) energy region and the presence of the low-energy MLCT (Rc → porphyrin (π*)) transitions in the visible region with energies higher than the predominantly porphyrin-centered Q-bands.

Synthesis and characterization of tetra-ganciclovir cobalt (II) phthalocyanine for electroanalytical applications of AA/DA/UA

Cobalt (II) phthalocyanine embedded with ganciclovir units has been synthesized by a novel method using tetracarboxylic phthalocyanine reported for the first time. The synthesized dark green colored complexes were characterized by electronic spectroscopy, elemental analysis, FT-IR, MASS and XRD. Thermal stability study reveals that the newly synthesized complex was stable up to 300 °C and XRD patterns showed amorphous nature of the complex. In the present work, the synthesized complex was characterized by cyclic voltammetry and shows the redox behavior corresponding to central metal (Co+II/Co+I) of the complex. Three biomolecules are well-separated by their oxidation peaks in simultaneous determination predicting the potentials for (-128, 335, and 723 mV) with highly increasing current. The low detection limit of AA, DA, and UA were 0.33, 0.03 and 0.10 μmol by CV method and good responses of amperometric and DPV technique. The modified tetra substituted CoTGPc/GCE exhibit an excellent electrocatalytic activity, stability, high sensitivity, good linearity, and selectivity without losing its catalytic activity and proves to be a versatile chemical sensor for commercial pharmaceutical samples, vitamin C tablets, and dopamine injections.

Electropolymerization of poly-5,10,15,20-tetrakis(p-aminophenyl)porphyrin in different deposition modes and solvents

The influence of solvent, supporting electrolyte and electrolysis modes on poly-5,10,15,20-tetrakis([Formula: see text]-aminophenyl)porphyrin film growth were studied by the quartz crystal microbalance method. Electropolymerization was carried out in potentiostatic and potentiodynamic modes from dichloromethane and ethanol solutions. Tetrabutylammonium perchlorate (TBAP) and tetrabutylammonium hexafluorophosphate (TBAHFP) were used as supporting electrolytes. Surface micrographs of films electrodeposited over a different number of cycles of potential variation were obtained. The specific surface area, the pore size, and the thickness of the obtained polyporphyrin films were determined. The number of electrons participating in 5,10,15,20-tetrakis([Formula: see text]-aminophenyl)porphyrin electropolymerization was determined by the quartz crystal microbalance method. Based on the electronic absorption spectroscopy results, it was established that porphyrin macroheterocycles were preserved in an oxidized state in polyporphyrin.

Switching of inter-valence charge transfer in stimuli-responsive bis(ferrocenyl)porphyrin

Stimuli-responsive 5,15-bis(ferrocenyl)-10,20-bis(mesityl)porphyrin (BFP) was synthesized and used to demonstrate the ON/OFF switching of inter-valence charge transfer (IVCT) between ferrocene terminals.