Ruthenium(II) Polypyridyl Complexes Coordinated Directly to the Pyrrole Backbone of π-Extended Boron Dipyrromethene (Bodipy) Dyes: Synthesis, Characterization, and Spectroscopic and Electrochemical Properties

Abstract

A series of new Bodipy dyes incorporating the π-extended isoquino[5,6-c]pyrrole have been synthesized and characterized. The dyes display intense Bodipy (π-π*) transitions and emissions with high quantum efficiencies. Spectroscopic, electrochemical, and theoretical calculations are used to give insight into the frontier orbitals. Coordination of {Ru(bpy)Cl} subunits to the peripheral isoquinol nitrogen atoms of the Bodipy dyes leads to three new bis-Ru(II)-polypyridyl-Bodipy complexes with the Ru(II) centers in direct contact with the dipyrrin core. Spectroscopic studies of the complexes reveal the traditional metal to ligand charge transfer (MLCT) transitions associated with Ru(dπ) to bpy(π*) transitions. However, a more intense transition above 600 nm is also observed. This transition is independent of the meso-substituents of the dipyrrin and is shifted to lower energy by as much as 25 nm compared to that of the Bodipy dyes without the Ru(II) subunits. Spectroscopic, electrochemical, and spectroelectrochemical studies suggest that the Bodipy π-orbitals are destabilized by coordination of the Ru(II) moieties. All three Ru-Bodipy complexes show the ability to generate singlet oxygen when irradiated within the photodynamic therapy window (600-850 nm) as evidenced by singlet oxygen trapping experiments.

Energy transfer in metal-exchange binuclear complexes covalently linked by asymmetric ligands

“…However, the heterometallic complexes C5 , C6 , C9 , and C10 exhibited four absorption bands in the range of 200–800 nm. The ligand-centered π → π* transitions of all complexes were observed in the range of 285 to 289 nm, 36–39 even though the transition involving the bipyridine ligand was expected to occur at a slightly higher energy than that involving the bridging ligand L. 40,41 All complexes exhibited broad MLCT absorption bands with moderate intensity at 234–255 and 450–460 nm, 42 due to the overlapping of the absorption spectra of the bridging ligand L and bipyridine. 43,44 For monometallic complexes C1 and C2 , we calculated their MLCT at 456 nm ( f = 0.443 for C1 and f = 0.040 for C2 ), in good agreement with the experimental value at 458 nm.…”

Evaluation of Endoplasmic Reticulum Targeting Isoquinol‐Based BODIPY Dyes and Their Properties as Molecular Rotors

“…Geometry optimizations were performed using Gaussian 16 [40] and GaussView 6.0.16 (64‐bit Linux) by employing density functional theory with the Becke3‐Lee‐Yang‐Parr hybrid functional B3LYP functional and the Pople valence double‐ζ 6‐31 g* basis set with a polarizable continuum model (PCM) to model bulk solvent effects. Use of B3LYP as a functional and 6‐31 g* as a basis set has been used for calculating the geometry of BODIPY compounds [41,42] . Default settings were chosen for convergence criteria for the geometry optimization.…”

“…Use of B3LYP as a functional and 6-31 g* as a basis set has been used for calculating the geometry of BODIPY compounds. [41,42] Default settings were chosen for convergence criteria for the geometry optimization. These optimizations were then subjected to frequency calculations at the same level of theory and structures were checked for imaginary frequencies in order to ensure that the calculated geometry represented a true energy minimum.…”

Bichromophoric Properties of Ruthenium(II) Polypyridyl Complexes Bridged by Boron Dipyrromethenes: Synthesis, Electrochemical, Spectroscopic, Computational Evaluation, and Plasmid DNA Photoreactions

“…For the past few years our laboratory has been interested in developing a bonding motif capable of accommodating a strong orbital interaction between ruthenium(II) polypyridyl complexes and BDP‐dyes. To this end, we have recently described the synthesis of three π‐extended isoquinol based BDP dyes as a bridging ligand coordinated to two {Ru II (bpy) 2 Cl} + moieties . The current report seeks to expand on this work and presents a modified synthetic route to generate two new π‐extended BDP‐dyes capable of serving as bridging ligands to Ru II polypyridyl complexes.…”

“…To this end, we have recently described the synthesis of three π-extended isoquinol based BDP dyes as a bridging ligand coordinated to two {Ru II (bpy) 2 Cl} + moieties. [35] The current report seeks to expand on this work and presents a modified synthetic route to generate two new π-extended BDP-dyes capable of serving as bridging ligands to Ru II polypyridyl complexes. Their synthetic, electrochemical, theoretical, and spectroscopic properties are presented along with evaluation of these complexes as potential photodynamic therapy (PDT) agents.…”