非对称双极性(D-π-A)吡啶 Salophen 席夫碱锌/镍配合物的合成、表征、线性及非线性光学性质研究

Synthesis, Characterization, Linear and Nonlinear Optical Effects of Nonsymmetrical Bipolar(D-π-A) Pyridyl Metallo Salophen Complexes

通过Still偶联反应合成了吡啶取代的香草醛(1a和1b)。以过渡金属离子(Zn2+和Ni2+)作为模板,以单亚胺席夫碱2和吡啶基香草醛为原料合成和表征了新的非对称双极性(D-π-A)Salophen金属配合物(3a、3b和3c)。测定了这些金属配合物的线性和三阶非线性光学(双光子吸收,TPA)性质。双极性的Salophen金属配合物的发射光谱在可见光范围内(486~516 nm),荧光寿命4.51 ns^5.18 ns,荧光量子产率在4.3%~5.3%之间。衰减时间测试表明,荧光寿命是在纳秒级范围,这表明该发射来自单线态。对这些化合物进行了热重分析,结果表明3a、3b和3c都是热稳定的,起始分解温度(Td)为333~374℃。使用开孔Z-扫描方法在800 nm处用100 fs脉冲的激光对这些双极性的Salophen金属配合物的TPA截面σ(2)进行了测试,最高可达1 403 GM,其值为目前已知席夫碱金属配合物较高值之一。测试表明,锌的Salophen金属配合物具有良好的荧光量子产率、巨大的TPA截面σ(2)、很高的热稳定性以及锌配合物公认的低毒性。因这些配合物可以被近红外或红外波长的光激发,这种光可以有效地穿透生物组织同时减轻细胞损伤,所以Salophen锌配合物作为双光子荧光发色团在生物体成像中有潜在的应用。

The pyridine substituent vanillins （1a and 1b） were synthesized by still coupling reaction. New unsymmetrical metallo Salophen complexes （3a, 3b and 3c） derived from the condensation of monoamine 2 and pyridine substituent salicylaldehyde in the presence of transition metal ions （Zn2＋, Ni2＋） as template have been synthesized and characterized. The linear and third-order non-linear optical （two photon absorption, TPA） properties of the complexes have been measured. The emission of （3a and 3c） were in the visible range（504~516 nm） with lifetime between 4.51 to 5.18 ns and quantum yields （Φem） between 4.3% to 5.3%. Decay times with nano-second scale indicate the emissions come from the singlet states. Complexes 3a, 3b and 3c are thermally stable with onset decomposition temperatures （Td） within the range of 333 to 374 ℃. 100 fs laser pulses with the open-aperture Z-scan method was used to measure the TPA cross-sections σ（2） of 3a, 3b and 3c at 800 nm. The σ（2） could reach to 1 403 GM, which is among the largest value known for metalloSalophen complexes to date. In general, these Salophen complexes show moderate fluorescence quantum yields, larger σ（2）, low cytotoxicity of zinc complexes and thermal stability. Hence, they are potentially good TPA candidates for tissue imaging work and excitation by NIR or longer-wavelength radiation is possible to increase penetration depth and reduce cell damage.