Mukherjee Soumalya, Prasad Edamana, Chadha Anju
Laboratory of Bioorganic Chemistry, Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India.
Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India.
Phys Chem Chem Phys. 2017 Mar 8;19(10):7288-7296. doi: 10.1039/c6cp08889a.
Bathochromic and hypsochromic shifts in the photo-luminescent spectra of doped and functionalized carbon nano-dots (CDs) arise due to the complex interaction between CDs and the solvent molecules around them. Nitrogen-functionalized carbon nano-dots (N-CDs) were synthesized from citric acid and urea using microwave assisted hydrothermal methods. Optical studies (absorption and photoluminescence) from the as-synthesized N-CDs were carried out in polar protic, aprotic and non-polar solvents. When excited at 355 nm, blue photoluminescence (PL) was observed from the N-CDs dispersed in polar aprotic solvents while green emission was observed in polar protic solvents. In addition to the general solvent effect, the analysis of the luminescence spectra in protic solvents suggests that hydrogen bonding plays a crucial role in regulating the photophysical characteristics of the system. Temperature dependent PL studies and time correlated single photon counting experiments in various solvent dispersions of N-CDs support the role of hydrogen bonding. This indicates that these results depend on the specific interactions observed from the N-CDs and can be thought of as the primary driving force which is then followed by solvent properties like dipole moments. Both the Lippert-Mataga model and Kamlet-Taft parameters were used to support the photophysical properties observed from N-CDs.
掺杂和功能化碳纳米点（CDs）的光致发光光谱中的红移和蓝移是由于CDs与其周围溶剂分子之间的复杂相互作用引起的。采用微波辅助水热法由柠檬酸和尿素合成了氮功能化碳纳米点（N-CDs）。对合成的N-CDs在极性质子溶剂、非质子溶剂和非极性溶剂中进行了光学研究（吸收和光致发光）。当在355nm激发时，在极性非质子溶剂中分散的N-CDs观察到蓝色光致发光（PL），而在极性质子溶剂中观察到绿色发射。除了一般的溶剂效应外，对质子溶剂中发光光谱的分析表明，氢键在调节体系的光物理特性中起着关键作用。N-CDs在各种溶剂分散体中的温度依赖PL研究和时间相关单光子计数实验支持了氢键的作用。这表明这些结果取决于从N-CDs观察到的特定相互作用，并且可以被认为是主要驱动力，随后是诸如偶极矩等溶剂性质。Lippert-Mataga模型和Kamlet-Taft参数都被用来支持从N-CDs观察到的光物理性质。
