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Newly synthesized nonconjugated, but covalently linked, bichromophoric systems (ADDSA) contain a salicylideneaniline (SA) moiety linked to an acridinedione (ADD) fluorophore via a covalent bond. The absorption and fluorescence characteristics of the ADDSA systems in various solvents reveal that the dual fluorescence originates from two different chromophores in the same molecule. The solvent polarity independent, long wavelength anomalous emission originates from the keto form of SA moiety via excited state intramolecular proton transfer (ESIPT). The ESIPT pathway was further confirmed by the benzylideneaniline (BA) and ADD moieties coupled non-proton transfer model system (ADDBA). Absence of the longer wavelength anomalous emission in the steady state as well as the shorter lifetime component in the time-resolved study for ADDBA system supports ESIPT mechanism for long wavelength anomalous emission in ADDSA system. ESIPT, discovered by Weller in 1955, has been the subject of continuous interest of researchers for more than five decades. 1 Photoinduced proton transfer, which is a representative of a limited number of adiabatic photochemical processes giving rise to fluorescence with an abnormally large Stokes shift, 2 plays an important role in biophysics, 3 and has practical application in technology, for example, in organic scintillators. 4 Among the molecular systems characterised by excited state proton transfer, both efficient organic photochromes 5 and polymer ultraviolet stabilisers 6 are of much interest. Prospects for the use of ESIPT systems in luminescent solar energy concentrators have also been discussed in literature. 7 For the ESIPT reaction to occur, it is necessary that proton-donor and proton-acceptor moieties be in close proximity and conjugated to one another in an organic molecule. ESIPT is considered as the driving force for the concerted enhancement of their acidity or basicity upon the transition to an excited state. 8 If a molecule carries its own base, excited-state proton transfer can occur intramolecularly and becomes more or less independent of the surrounding solvent. ESIPT reaction is extremely fast (subpicosecond kinetics) and also occurs in rigid glasses and at very low temperatures. 9 Very often, only the ESIPT product (P Ã ) fluoresces, and this is the source of extremely large Stokes shift, which are fairly independent of medium and temperature. Thus, ESIPT dyes are ideal candidates for use as fluorescence labels in order to avoid interference from other fluorescent material present in the sample to be analyzed.Most of the publications on ESIPT deal with derivatives of salicylic acid, its esters and amides, 10 salicylaldehyde, acetophenone and related compounds, 11 o-hydroxybenzoxazoles, 12 benzothiazoles, 13 triazoles, 14 flavonols, 15 anthraquinones, 16 bipyridyls, 17 and malonic aldehyde. 18 Recently, Chou et al. have studied the solvent polarity tuned excited state, charge-transfer-coupled proton transfer reaction in p-N,N-ditolylaminosalicylaldehyde-and 3-hydroxyflavone-ba...

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Huntington’s disease (HD) causes progressive movement disorders and cognitive deficits. Besides, sleep disturbances and emotional distress are prominent clinical signatures of HD. The experimental subjects and HD human brains display altered regenerative plasticity resulting from aberrant neurogenic and nonneurogenic areas. Sleep disorders, emotional disruption, and cognitive deficits have been linked to impaired cell cycle events of neural stem cells (NSC) in neurodegenerative disorders. In a physiological state, circadian clock gene pathways play important roles in the regulation of the proliferation and differentiation of NSC, whereas the irregular circadian clock pathway is attributed to impairment in the neurogenic process. The recent advancement of chemogenetic-based approaches represents a potential scientific tool to rectify the abnormal circadian clock which may aid in mitigating neurogenic failure in the brain. Notably, GABAergic vasoactive intestinal peptide (VIP)-expressing neurons in the brain plays a key role in the regulation of neuroplasticity and circadian rhythm. Thus, this conceptual review article addresses the potential link between sleep disorder and aberrant neurogenic events in HD and proposes chemogenetic kindling of vasoactive intestinal peptide (VIP) -expressing GABAergic neurons in the brain as a therapeutic strategy for reprogramming the clock gene pathways in mitigating the neurodegenerative failure in HD.