Synthesis, photophysicochemical and photodynamic antimicrobial chemotherapy studies of indium pyridyl phthalocyanines: Charge versus bridging atom

Simultaneous Prediction of the Energies of Qx and Qy Bands and Intramolecular Charge-Transfer Transitions in Benzoannulated and Non-Peripherally Substituted Metal-Free Phthalocyanines and Their Analogues: No Standard TDDFT Silver Bullet Yet

“…Significant interest in the chemistry and spectroscopy of phthalocyanines (Pcs) and their analogues primarily originates from their wide array of applications that vary from their traditional use as blue or green dyes and pigments , to more recent applications in oxidative catalysis, − photodynamic therapy of cancer, − antimicrobial and antibacterial phototherapy, − nanotechnology, − chemical sensing, − materials chemistry, − and nonlinear optics. − The majority of these applications are related to the unique optical properties of Pcs and their analogues and specifically the intense, low-energy Q -band observed in the visible or NIR region, which represents the first excited state in systems with effective 4-fold symmetry. In the case of metal-free or low-symmetry Pcs and their analogues, the doubly degenerate first excited state of 1 E u symmetry splits into two components with x - and y -polarization (keeping z -axis perpendicular to the macrocycle plane), which results in the splitting of the Q -band into Q x - and Q y -transitions. , The energy of the Q -band(s) in Pcs and their analogues can be tuned up by two general methods: (i) by a stepwise increase or decrease of the aromatic π-system in Pcs by the addition or elimination of the annulated benzene rings in Pcs; (ii) by the introduction of substituents into the Pc core. − In the first case, the Q -band position (or Q -band center taken as the average energy between Q x - and Q y -transitions) shifts by ∼100 nm going from tetraazaporphyrin (TAP) to Pc to 2,3-naphthalocyanine (Nc) to anthracocyanine (Ac) systems (Figure ).…”