Ping-Pong Energy Transfer in a Boron Dipyrromethane Containing Pt(II)–Schiff Base Complex: Synthesis, Photophysical Studies, and Anti-Stokes Shift Increase in Triplet–Triplet Annihilation Upconversion

Abstract

A boron dipyrromethane (BDP)-containing Pt(II)-Schiff base complex (Pt-BDP), showing ping-pong singlet-triplet energy transfer, was synthesized, and the detailed photophysical properties were investigated using various steady-state and time-resolved transient spectroscopies. Femtosecond/nanosecond transient absorption spectroscopies demonstrated that, upon selective excitation of the BDP unit in Pt-BDP at 490 nm, Förster resonance energy transfer from the BDP unit to the Pt(II) coordination center occurred (6.7 ps), accompanied by an ultrafast intersystem crossing at the Pt(II) coordination center (<1 ps) and triplet-triplet energy transfer back to the BDP moiety (148 ps). These processes generated a triplet state localized at BDP, and the lifetime was 103.2 μs, much longer than the triplet-state lifetime of Pt-Ph (3.5 μs), a complex without the BDP moiety. Finally, Pt-BDP was used as a triplet photosensitizer for triplet-triplet annihilation (TTA) upconversion through selective excitation of the BDP unit or the Pt(II) coordination center at lower excitation energy. An upconversion quantum yield of up to 10% was observed with selective excitation of the BDP moiety, and a large anti-Stokes shift of 0.65 eV was observed upon excitation of the lower-energy band of the Pt(II) coordination center. We propose that using triplet photosensitizers with the ping-pong energy-transfer process may become a useful method for increasing the anti-Stokes shift of TTA upconversion.

TREPR Study of the Anisotropic Spin–Lattice Relaxation Induced by Intramolecular Energy Transfer in Orthogonal BODIPY Dimers

“…Thus, we envisage the T 1 states of the two units are very close in energy, , and it is difficult to observe the intramolecular singlet energy transfer and triplet energy transfer with transient optical spectroscopies . This scenario is drastically different from the polyads in which the subunits are with significantly different T 1 state energy levels, so that the intramolecular triplet state energy transfer can be clearly detected. − …”

Novel zinc (II) and nickel (II) complexes of a quinazoline‐based ligand with an imidazole ring: Synthesis, spectroscopic property, antibacterial activities, time‐dependent density functional theory calculations and Hirshfeld surface analysis

“…UV/VIS spectra were recorded in a Shimadzu UV-2550 spectrophotometer. 1 H NMR spectra of ligand were tested in DMSO-d6 on a Mercury Plus (400 MHz) spectrometer. Single-crystal X-ray diffraction analysis was carried out using a Rigaku Oxford Diffraction.…”

“…Supramolecular chemistry involving significant transition metal complexes is of great interest to the crystal engineering community since their potential applications as optics materials, [1,2] catalysis, [3,4] molecular magnetic materials, [5,6] luminescent materials, [7] molecular sensors, [8] and so on, which have received a widespread attention especially in the last decade. Heterocyclic ligands containing quinazoline ring was used widely as special scaffolds of bioactive molecules and inorganic syntheses.…”

“…In previous work, several studies on the properties of copper (II) and cobalt (II) complexes have been reported. [19,20] As an continuation of our research, herein we mainly report synthetic routes (Scheme 1), characterization and biological activity of complexes [Zn (L) 2 (CH 3 OH) 2 ](NO 3 ) 2 (1) and [Ni(L) 3 ]Á(NO 3 ) 2 (2) with 2-(2-imidazolyl)-4-methyl-1,2-dihydroquinazoline-N 3 -oxide ligand (L). Zn (II) and Ni (II) complexes were characterized by X-ray crystallographic analysis and in both the metals show a six-coordination geometry.…”

Porphyrin‐Ryleneimide Hybrids: Low‐Bandgap Acceptors in Energy‐Transfer Cassettes

“…Donor-acceptor assemblies consisting of large, π-conjugated chromophores have attracted widespread interest as mimics of light-harvesting and electron-transfer systems found in living organisms. [1][2][3][4] Artificial multichromophoric structures containing photoactive subunits have been extensively investigated as materials for solar energy conversion. [5] Many of those bioinspired systems employ porphyrins and other oligopyrrole building blocks, because of their structural resemblance to chlorophylls found in natural photosynthetic centers.…”