title: Switching of emission of a styryl dye in cucurbit[7]uril: a comprehensive experimental and theoretical study.
abstract: Intriguing colour change and change in fluorescence band of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide from nonpolar to polar protic solvent, and also from molecular container cucurbit[7]uril environment to polar protic solvent has been reported here. This interesting colour change of this dye with respect to the medium makes this dye useful as a sensor. Change in spectral characteristics of DASPMI along with change of colour from orange to yellow with increasing polarity of medium is interpreted as due to negative solvatochromatism. Complexations of probe-cucurbit[7]uril (1:1 and 2:1) cause structural change of the probe molecule due to hydrogen bond interaction of cationic part of the dye with CO group of cucurbit[7]uril and the colour change of the solution ensued. On addition of sodium chloride to the inclusion complex the dye is released from cucurbit[7]uril interior with colour of the solution reverted back. Theoretical results show that one carbon atom in the styryl part containing the positive charge gets too close to a carbon atom of cucurbit[7]uril to cause a phenomenal increase of dipole moment by 10X.
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
authors.forename: Anamika
authors.initials: A
authors.lastname: Manna
authors.affiliation: Department of Spectroscopy, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India. Electronic address: spsc@iacs.res.in.
authors.forename: Sankar
authors.initials: S
authors.lastname: Chakravorti
mesh_terms: D001952:Bridged-Ring Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000008:administration & dosage / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D007454:Iodides / Q000008:administration & dosage / Q000737:chemistry*; D008958:Models, Molecular; D011522:Protons; D011726:Pyridinium Compounds / Q000008:administration & dosage / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D001952:Bridged-Ring Compounds; D004396:Coloring Agents; D007093:Imidazoles; D007454:Iodides; D011522:Protons; D011726:Pyridinium Compounds; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils; C011786:2-(4-(dimethylamino)styryl)-1-methylpyridinium
keywords: 1:1 complexation; 2-(4-(Dimethylamino)styryl)-1-methylpyridinium iodide; 2:1 complexation; Cucurbit[n]uril; Deprotonation; Negative solvatochromism