title: Synthesis and Photophysical Studies on Naphthalimide Derived Fluorophores as Markers in Drug Delivery.
abstract: Derivatives of 4-amino-1,8-naphthalimide containing a free alkyl chain bearing carboxyl group as linker and different substituents at 4-amino function have been synthesized, characterized and studied for their photophysical properties. Steady state fluorescence studies showed quantum yield varied from 0.45 to 0.65 with Stokes shift in the range of 5824-8558 cm(-1). Spectroscopic and physicochemical parameters, like electronic absorption, emission, and extinction coefficient were investigated in order to explore the analytical potential of compounds. Solvatochromic studies demonstrated that all compounds were sensitive towards the polarity of different solvents showing the highest degree of fluorescence in acetonitrile. In addition, the compounds in the presence of ions, viz. Na(+), K(+) and Mg(2+) at concentration of 0.1-2 equivalents, showed a decreasing trend in fluorescence with increasing ionic concentration. TCSPC set - up was used to measure the fluorescence lifetime of compounds, which was found to be bi-exponential with longer and shorter component at their respective amplitudes. The average lifetime of compounds was observed to be 5.76-9.96 ns indicating the possibility of their greater utilization in research and diagnosis.
authors.affiliation: Bioorganic Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad, 211002, India.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Singh
authors.affiliation: Bioorganic Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad, 211002, India.
authors.forename: Ritika
authors.initials: R
authors.lastname: Srivastava
authors.affiliation: Bioorganic Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad, 211002, India.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Singh
authors.affiliation: Bioorganic Research Laboratory, Department of Chemistry, University of Allahabad, Allahabad, 211002, India. rksinghsrk@gmail.com.
authors.forename: Ramendra K
authors.initials: RK
authors.lastname: Singh
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D060326:Chemistry Techniques, Synthetic; D016503:Drug Delivery Systems; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry*; D053644:Naphthalimides / Q000138:chemical synthesis* / Q000737:chemistry*; D015363:Quinolones / Q000138:chemical synthesis* / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes; D053644:Naphthalimides; D015363:Quinolones; C086538:4-amino-1,8-naphthalimide; D015057:1-Naphthylamine
keywords: Amino-naphthalimide derivative; Average lifetime; Quantum yield; Solvatochromism; Steady state fluorescence