Steric-controlled excimer formation in naphthalene analogues of chalcone.
Naphthalene analogues of chalcone (typical vinylarenes) are well known for their intramolecular charge transfer (CT) process. The all four possible isomers NC1, NC2, NC3 and NC4 were observed to give structure-less broad CT bands, whereas, excimer formation at higher concentration was reported only for NC4 [Res. Chem. Intermed. 25 (1999) 903]. However, conventional GMMX calculation data reveals that the naphthalene portion of all the isomers are planar, hence, excimer emission is expected from all of them, i.e., if NC4 can form an excimer, then the rests are also capable of doing it. In this paper we have actually succeeded in resolving the excimer peaks for all these four isomers by optimization of concentration, though the extent of excimer formation was observed to be the maximum for NC4. These differential tendencies of excimer formation can be explained by the change in extent of intermolecular stacking interaction of the naphthalene moieties. Variation occurs here due to steric perturbation arising from the specific orientation of the near resident non-planar aroyl component with respect to the naphthalene moiety.
Chatterjee
Suchandra
S
Department of Chemistry, Serampore College, Serampore, Hooghly 712204, India.
Kar
Samiran
S
Lahiri
Saswati
S
Basu
Samita
S
D002599:Chalcone / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D010777:Photochemistry; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013237:Stereoisomerism; D013816:Thermodynamics
D009281:Naphthalenes; D002599:Chalcone