Two-Photon Absorption and Fluorescence in Micrometer-Sized Single Crystals of a Rhodamine B Coordinated Metal–Organic Framework

A Rhodamine B (RhB) dye coordinated, 2D metal–organic framework (MOF), {[Zn2(L)­(RhB)]·5DMF}n (1; DMF = N,N-dimethylformamide), was constructed solvothermally from a −NH2-functionalized ligand and ZnII ions. The MOF features interlayer π···π interaction between the RhB molecules with an overlap of almost 100%. One- and two-photon-excited fluorescence measurements were carried out on micrometer-sized single crystals of varied thickness with continuous-wave and femtosecond pulsed lasers, respectively. The two-photon absorption coefficient was measured relative to the CdS crystal and found to be 7.1 ± 0.7 cm/GW at a wavelength of 1030 nm. Our findings demonstrate a new way of achieving solid-state dye microlasers or microsized light-frequency upconverters.本研究通过溶剂热法，以-NH₂官能化配体与Zn(II)离子为原料，构筑了一例罗丹明B（Rhodamine B, RhB）配位的二维金属有机框架（metal–organic framework, MOF），其化学式为{[Zn₂(L)­(RhB)]·5DMF}n（产物编号1；DMF = N,N-二甲基甲酰胺）。该MOF的层间存在π···π相互作用，RhB分子间的重叠程度近乎100%。分别采用连续波激光器与飞秒脉冲激光器，对不同厚度的微米级单晶开展了单光子激发与双光子激发荧光测试。以硫化镉（CdS）晶体作为参比标准，测得该样品在1030 nm波长下的双光子吸收系数为7.1 ± 0.7 cm/GW。本研究结果为固态染料微激光器或微米级光频率上转换器件的开发提供了全新途径。