Triple emission from p-dimethylaminobenzonitrile-cucurbit[8]uril triggers the elusive excimer emission.
The intriguing dual-emission behavior of p- dimethylaminobenzonitrile (DMABN) and the identity of the associated excited states is, arguably, the most extensively investigated and also controversially discussed molecule- specific phenomenon of modern photochemistry. We have now found a new, third fluorescence band when DMABN is encapsulated within the water-soluble molecular container cucurbit[8]uril (CB8). It is centered between the previously observed emissions and assigned to the elusive excimer emission from DMABN through 1:2 CB8:DMABN complex formation. Heating of the CB8⋅(DMABN)2 complex from 0 to 100 °C results in the dissociation of the ternary complex and restoration of the dual-emission properties of the monomer. Alternatively, monomer emission can be obtained by selecting cucurbit[7]uril (CB7), a host homologue that is too small to accommodate two DMABN molecules, or by introducing ethyl instead of methyl groups at the amino terminus of the aminobenzonitrile guest.
Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India), Fax: (+91) 22-25505151/25519613.
Mhejabeen
M
Sayed
Frank
F
Biedermann
Vanya D
VD
Uzunova
Khaleel I
KI
Assaf
Achikanath C
AC
Bhasikuttan
Haridas
H
Pal
Werner M
WM
Nau
Jyotirmayee
J
Mohanty
host-guest systems; macrocycles; multiemissive chromophores; photophysics; supramolecular chemistry