Dual-Emissive Bis(diphenylphosphino)amine Platinum Complexes: Structural, Reactivity, Photophysical, and Theoretical Investigations

Abstract

By the reactions of bis(diphenylphosphino)amine (dppa) with equimolar amounts of cycloplatinated(II) complexes 1 with two neutral (SMe 2 or DMSO) and anionic (Cl − or CF 3 CO 2 − ) labile ligands the bis-chelate complexes 2 with a chelating mode of dppa were synthesized that have one of the smallest bite angles in a diphosphine. As the usual strategy for synthesizing the binuclear complexes, the reactions of 0.5 equiv of dppa with cycloplatinated(II) complexes 1 with a Cl − ligand were successful in making symmetrical binuclear complexes. Also, the chelating dppa has a strong angle strain that makes it a susceptible precursor for biphosphine ring opening. Furthermore, this new strategy was successful for designing symmetrical and unsymmetrical binuclear complexes with Cl − ligands. Interestingly, all efforts to make binuclear complexes with bridging dppa from precursors that contain CF 3 CO 2 − were unsuccessful by both strategies. The effects of dimerization via a change in the coordination mode of dppa, from a chelate mode in complexes 2 with green emission to a bridge mode in complexes 3, with dualphosphorescence red emission were investigated in the powder and poly(methyl methacrylate) (PMMA) phases at 77 and 298 K. The emission decay curves of all complexes in the solid state show long and short lifetime values as characteristics of the triplet excited states. The reaction pathway, reactivity, and structural aspects of the complexes were compared with those of other similar dppm analogues and the mechanism of conversion via possible intermediates was considered by density functional theory (DFT) calculations. For interpretation of the emission spectra, time-dependent DFT (TD-DFT) calculations were carried out on the isolated and stacked forms.

A Carbazole-Bridged Biscyclometalated Diplatinum Complex: Synthesis, Characterization, and Dual-Mode Aggregation-Enhanced Phosphorescence

“…The dodecyl chains were bent from the two lateral sides and toward the top and bottom side of the dimeric structure, respectively. Although a number of diplatinum complexes have been reported to date, − such a dimeric structure with double Pt–Pt interactions is unprecedented to the best of our knowledge.…”

“…In addition to the commonly reported monoplatinum complexes, the syntheses and applications of bridged diplatinum complexes have been the focus of some recent works. − Depending on the ligand structure, these complexes may exhibit a rigid planar, folded, or flexible conformation. − In the latter two cases, the conformation of bridged diplatinum complexes may change in response to external conditions such as solvents, metal ions, or light, which can be utilized to realize sophisticated and/or switchable assembly. − In the case of diplatinum complexes with a rigid planar bridge, a red shift of the emission wavelength may be expected due to the extension of conjugation. In addition, these complexes typically possess a larger molecular plane with respect to monoplatinum complexes, which are expected to enhance the intermolecular interaction and thus be beneficial for assembly.…”

Temperature-dependent excited states for detecting reversible phase transitions in 2D lead(ii) iodide perovskites

“…The presence of two resolved peaks in the absorption and PL emission spectra could originate from the dual excitonic emission, vibronic coupling, simultaneous coexistence of the two crystallographic phases, or temperature-induced exciton switching in these compounds. [37][38][39][40][41][42] The robust absorbance aligned with both PL peaks implies that neither of the two PL peaks stems from defect states. Typically, emissions linked to defects or traps lack the corresponding absorption, as localized defect states exhibit a notably low absorption cross-section.…”

Multistimuli-responsive multicolor solid-state luminescence tuned by NH-dependent switchable hydrogen bonds

“…Both bis(diphenylphosphine) amine (dppa) and 5-tert-butyl-3-(2′-pyrimidinyl)-1H-1,2,4-triazole (bpmtzH) feature an N-H functional group that readily yields hydrogen bonding with neighbouring solvent molecules and counter-ions. 26,[34][35][36][37][38][39] Hence, it is feasible to construct multistimuli-responsive luminescent materials of Cu(I) complexes by using hydrogen bonding with those two distinct N-H groups from dppa and bpmtzH, since the forming and breaking of hydrogen bonding with those two different N-H groups affect the HOMO and LUMO energy levels to varying degrees.…”