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Synthesis, Structure, Photophysical Properties, and Photostability of Benzodipyrenes
摘要： We explored the syntheses, structure, photophysical properties, and photostability of benzodipyrenes (BDPs). BDPs were synthesized through an InCl3-AgNTf2 catalyzed, four-fold alkyne benzannulation reaction. The structures of BDP 4a and its corresponding endoperoxide product were unambiguously confirmed by X-ray crystallography. The BDPs reported here can also be recognized as peri- and cata-benzannulated pentacenes with a non-functionalized central ring. Unlike the previous reported pentacene-based polycyclic aromatic hydrocarbons, the absorbance of the BDPs was blue-shifted by ca. 40 nm relative to pentacene, even after extension of π–conjugation. The newly synthesized BDP products exhibit good relative stability with half-lives as high as 4612 min in THF.
关键词： pentacene,benzannulation,alkyne,singlet oxygen,photostability
更新于2025-09-10 09:29:36
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Butterfly in a Flask: Irregular Nanographenes by Highly Regioselective Domino Benzannulation
摘要： A highly regioselective domino benzannulation reaction of conjugated 1,3-diynes was developed by Chalifoux and co-workers to access irregular nanographene moieties. Notably, to demonstrate the efficiency of the reaction, a chiral butterfly-shaped ligand precursor was successfully synthesized through a fourfold alkyne benzannulation of a bis-buta-1,3-diyne. This method opens new avenues for tuning and studying the properties of nanographenes as a function of shape.
关键词： conjugated diynes,domino benzannulation,nanographenes
更新于2025-09-09 09:28:46
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Effects of Varying the Benzannulation Site and π Conjugation of the Cyclometalating Ligand on the Photophysics and Reverse Saturable Absorption of Monocationic Iridium(III) Complexes
摘要： A series of monocationic iridium(III) complexes, [Ir(C^N)2(pqu)]+PF6? [pqu = 2-(pyridin-2-yl)quinoline, C^N = 2-phenylquinoline (1), 3-phenylisoquinoline (2), 1-phenylisoquinoline (3), benzo[h]quinoline (4), 2-(pyridin-2-yl)naphthalene (5), 1-(pyridin-2-yl)naphthalene (6), 2-(phenanthren-9-yl)pyridine (7), 2-phenylbenzo[g]quinoline (8), 2-(naphthalen-2-yl)quinoline (9), and 2-(naphthalen-2-yl)benzo[g]quinoline (10)], were synthesized in this work. These complexes bear C^N ligands with varied degrees of π conjugation and sites of benzannulation, allowing for elucidation of the effects of the benzannulation site at the C^N ligand on the photophysics of the complexes. Ultraviolet?visible (UV?vis) absorption and emission of the complexes were systematically investigated via spectroscopic techniques and time-dependent density functional theory calculations. Their triplet excited-state absorption and reverse saturable absorption (RSA) were studied by nanosecond transient absorption (TA) spectroscopy and nonlinear transmission techniques. The fusion of phenyl ring(s) to the phenyl ring or the 4 and 5 positions of the pyridyl ring of the C^N ligand resulted in red-shifted UV?vis absorption and emission spectra in complexes 2, 5?7, 9, and 10 compared to those of the parent complex 0, while their triplet lifetimes and emission quantum yields were significantly reduced. In contrast, the fusion of one phenyl ring to the other sites of the pyridyl group of the C^N ligand showed an insignificant impact on the energies of the lowest singlet (S1) and triplet (T1) excited states in complexes 1, 3, and 4 but noticeably affected their TA spectral features. The fusion of the naphthyl group to the 5 and 6 and positions at the pyridyl ring did not influence the S1 energy of complex 8 but altered the nature of the T1 states in 8 and 10 by switching them to the benzo[g]quinoline-localized 3π,π* state, which resulted in completely different emission and TA spectra in these two complexes. The site-dependent variations of the ground- and excited-state absorption induced strong but varied RSA from these complexes for 4.1-ns laser pulses at 532 nm, with the RSA strength decreasing in the trend of 3 > 7 ≈ 4 ≈ 9 ≈ 6 > 8 ≈ 1 ≈ 2 ≈ 5 > 10.
关键词： iridium(III) complexes,time-dependent density functional theory,spectroscopic techniques,photophysics,reverse saturable absorption,benzannulation
更新于2025-09-04 15:30:14