Two novel phenanthro [9,10-d]imidazole substituted metal phthalocyanines, ImCuPc and ImZnPc, have been synthesized and their potential as photosensitizers has been investigated through optical, electrochemical, and ultrafast nonlinear optical (NLO) studies, including their excited state dynamics. The absorption as well as emission spectra of both the title compounds exhibited negligible Stokes shift in different solvents. The molecules depicted a broad Soret band due to the incorporation of phenanthro[9,10-d]imidazole moiety while the Q-bands were characteristic to their metal phthalocyanine group. DFT studies elucidated the HOMO-LUMO (4.99–2.90 eV) levels of these molecules with their energy optimized structures generated using DFT, TD-DFT analysis. The fs-TAS spectra of both the molecules exhibited contribution from singlet-singlet excited state absorption followed by transition to triplet states via intersystem crossing, ISC. The lifetimes calculated from obtained kinetics at specific wavelengths using global fitting demonstrated slow singlet to triplet state intersystem crossing in ImCuPc (decay rate of 1.6 × 10⁸ s⁻¹) and ImZnPc (decay rate of 1.4 × 10⁸s⁻¹). The ns-TAS studies established long lived triplet states in both the molecules with ImCuPc depicting a slightly higher triplet lifetime of ~1.4 μs over ImZnPc with a triplet lifetime of ~1.2 μs The triplet quantum yields (φ_T) were calculated to be 0.51 for ImCuPc while it was 0.27 for ImZnPc suggesting ImCuPc to be a better photosensitizer (PS) over ImZnPc. We believe the intramolecular D-π-A interaction is stronger in ImCuPc resulting in higher triplet yield. Third-order NLO studies performed at a non-resonant excitation of 800 nm (~50 fs, 1 kHz pulses) demonstrated ImZnPc had a larger two-photon absorption cross-section (994 GM), possibly due to heavy atom effect, while ImCuPc was found to possess superior n₂ (3.7 × 10⁻¹⁵ cm²/W). The slightly superior nonlinear optical (NLO) performance of ImCuPc over ImZnPc could also possibly be due to lower energy gap and Copper's open 3d shells as opposed to full 3d shell in Zinc which overlaps with Pc 2p shells making it more active.

已合成了两种新型的邻苯并[9,10-d]咪唑取代的金属酞菁，并通过光学，电化学和超快非线性光学（NLO）研究了其作为光敏剂的潜力，包括其激发态动力学。两种标题化合物的吸收光谱和发射光谱在不同溶剂中的斯托克斯位移均可以忽略不计。由于结合了菲咯啉[9,10-d]咪唑部分，该分子表现出较宽的索雷特谱带，而Q谱带是其金属酞菁基团的特征。DFT研究阐明了这些分子的HOMO-LUMO（4.99–2.90 eV）水平及其通过DFT，TD-DFT分析生成的能量优化结构。两种分子的fs-TAS光谱均表现出单峰-单峰激发态吸收，然后通过系统间交叉ISC转变为三重态。使用整体拟合从在特定波长下获得的动力学计算得出的寿命表明，ImCuPc的单重态到三重态系统间跨度慢（衰减率为1.6×10⁸ s ^-1）和ImZnPc（衰减率为1.4×10 ⁸ s ^-1）。对NS-TAS研究确定长期生活在两个分子的三重态与ImCuPc描绘〜稍高三线态寿命1.4微秒以上ImZnPc用〜1.2微秒的三重态的量子产率的三线态寿命（φ _Ť）的计算得出ImCuPc的光敏剂（ImCuPc）为0.51，而ImZnPc的ImCuPc为0.27，这表明ImCuPc比ImZnPc更好。我们认为ImCuPc中的分子内D-π-A相互作用更强，从而导致更高的三重态产率。在800 nm（〜50 fs，1 kHz脉冲）的非共振激发下进行的三阶NLO研究表明，ImZnPc具有较大的双光子吸收截面（994 GM），这可能是由于重原子效应引起的，而ImCuPc被发现具有优异的n ₂（3.7×10 ^-15  cm ² / W）。ImCuPc的非线性光学（NLO）性能略高于ImZnPc，这也可能是由于较低的能隙和铜的开放3d壳（而不是锌中的全3d壳）与Pc 2p壳重叠而使其更具活性所致。