Khurana Raman, Agarwalla Sandeep, Sridhar G, Barooah Nilotpal, Bhasikuttan Achikanath C, Mohanty Jyotirmayee
Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India.
Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai, India.
Chemphyschem. 2018 Sep 18;19(18):2349-2356. doi: 10.1002/cphc.201800373. Epub 2018 Jun 27.
Although aqueous dye lasers are much sought after, they have been of no practical use, as laser dyes show a strong tendency for aggregation in water, thus diminishing their optical output. Contributing towards this shortcoming, we studied the noncovalent interactions of two prominent laser dyes, namely, rhodamine 6G and rhodamine B, with a water soluble macrocyclic host, sulfobutylether-β-cyclodextrin (SBE βCD). Spectral changes in the absorption and fluorescence behavior of dyes in presence of the SBE βCD host indicated adequate complex formation between dye and host (K∼10 M ). A combination of various photophysical parameters evaluated from measurements such as Job plot, changes in the fluorescence lifetime/anisotropy values, and favorable thermodynamic parameters from isothermal titration calorimetric measurements adjudicated a 1 : 1 stoichiometric complex formation between dye and SBE βCD host. Consequently, SBE βCD prevents dye aggregation/adsorption and present rhodamine dyes in their monomeric forms with enhanced fluorescence yield and brightness. These vital parameters were utilized to optimize and demonstrate cost-effective supramolecular broad-band and narrow-band aqueous dye laser systems with improved lasing efficiencies (∼25 % higher for the SBE βCD : RhB system and ∼10 % higher for SBE βCD : Rh6G system), better beam profile, and enhanced durability compared to the respective dyes in optically matched ethanol solutions.
尽管水性染料激光器备受追捧，但它们一直没有实际用途，因为激光染料在水中表现出强烈的聚集倾向，从而降低了它们的光学输出。为了解决这一缺点，我们研究了两种著名的激光染料，即罗丹明6G和罗丹明B，与水溶性大环主体磺丁基醚-β-环糊精（SBE βCD）的非共价相互作用。在SBE βCD主体存在下，染料吸收和荧光行为的光谱变化表明染料与主体之间形成了足够的复合物（K∼10 M）。通过诸如Job曲线测量、荧光寿命/各向异性值变化等测量评估的各种光物理参数，以及等温滴定量热测量得到的有利热力学参数，判定染料与SBE βCD主体之间形成了1:1化学计量比的复合物。因此，SBE βCD可防止染料聚集/吸附，并使罗丹明染料以单体形式存在，具有更高的荧光产率和亮度。利用这些关键参数优化并展示了具有成本效益的超分子宽带和窄带水性染料激光系统，与光学匹配的乙醇溶液中的相应染料相比，其激光效率提高（SBE βCD:RhB系统高约25%，SBE βCD:Rh6G系统高约10%），光束轮廓更好，耐久性增强。
