Recent demonstration in augmenting the efficiency of aqueous Rhodamine dye lasers using cucurbit[7]uril (CB[7]), a deaggregating and photostabilizing host, has drawn interest in the synthesis and characterization of spectroscopic grade CB[7] in larger quantities. Synthesis of cucurbituril group of macrocycles always leads to the formation of various homologues of CB[n]s (n=5–7) with CB[7] as the minor product. The literature procedure has been optimized to get pure CB[7] in 12–14% yield by fractional crystallization and the purity was checked by NMR, MS and spectrophotometric titration. Laser performances of the synthesized and commercial CB[7] sample as an additive were evaluated using Nd-YAG (532 nm) pumped Rhodamine B aqueous dye lasers and comparable results were obtained.

Quantum yield of fluorescence (QYF) of widely used Rhodamine (RhB) dye in ethanol and water was observed to decrease rapidly with increase in temperature of the dye solutions, which was correlated to enhanced torsional motion of its flexible diethylamino groups. This is harmful for its use in high-average power dye lasers, pumped by copper vapour laser (CVL) or diodepumped solid-state green laser (DPSSGL), in which bulk temperature of the dye solution was found to increase due to the heat generated by circulation pumps and non-radiative decay processes of excited dye molecules. The QYF of RhB dye in water was found to be not sensitive to temperature in the practical operating region 16–25°C of dye laser by adopting supramolecular route to form an inclusion complex of RhB with the container molecule cucurbit[7]uril (CB[7]).