Photophysical properties of pyridinium salts derived from purine bases

Abstract

. Can. J. Chem. 68, 2164Chem. 68, (1990.The absorption spectra, fluorescence spectra, fluorescence lifetimes, fluorescence quenching, phosphorescence spectra, phosphorescence lifetimes, and picosecond transient absorption spectra of several purinyl-pyridinium salts have been measured in several solvents at room temperature and in ethanol glasses at 77 K. It is concluded that the previously observed photochemical transformation of N-[9-(2',3',5'-tri-O-acetyl-P-~-ribofuranosyl)purin-6-yl]pyridinium chloride 1 into the highly fluorescent tri-0-acetylluminarosine 6 occurs via an excited triplet state. It is also shown that intersystem crossing in purinyl-pyridinium salts is induced by an intermolecular charge-transfer interaction with the counter ions.

Microwave-Assisted Synthesis, Optical and Theoretical Characterization of Novel 2-(imidazo[1,5-a]pyridine-1-yl)pyridinium Salts

“…The drastic reduction of φ reported upon formation of pyridinium salts is in agreement with data reported for similar compounds [50]. Upon quaternization, the radiative decay constant (k rad ) of 1 decreased from 3.65 × 10 7 s −1 to 1.73 × 10 7 s −1 in 1q, while the nonradiative constant followed the opposite trend-Table 1.…”

Fluorescent nucleoside derivatives: Luminescence study of 4-dimethylaminopyridinium chloride derived from guanosine

“…The high deuterium isotope effect points to the involvement of the excited-state proton transfer reaction in the quenching mechanism. Contrary to previously studied pyridinium salts 1 in Rt=H series, which are efficiently quenched by a number of inorganic ions (CI-, Br-, I-, SO4 -2)[3], the fluorescence of GDMAP is Stern-Volmer plots for fluorescence quenching of GDMAP by iodide ions. Changes in the UV speca'um of GDMAP in water upon the addition of adenosine.quenched exclusively, by I-.…”

“…1). Both UV absorption and fluorescence parameters in water do not change over the wide pH range (1)(2)(3)(4)(5)(6)(7)(8)(9). The emission of GDMAP in water is weak but increases sit, nifieanfly in ]320, alcohols, and, particularly, aeetonitrile.…”

“…Pyridinium derivatives of purine and pyrimidine nucleosides are a family of ionic compounds of the following general structures: Scheme I Both purine, 1, and pyrmidine, 2, derivatives in the R1 = H series, have already been shown to possess interesting chemical [1], photochemical [2], and photoplays- ieal [3] properties. Among the N,N-dimethylaminopyridinium derivatives which have been synthesized recently [4], of particular interest is that derived from guanosine [Rm=N(CH3)2, R2=NH2], abbreviated GDMAP.…”

Synthetic Strategies Towards O6-Substituted Guanine Derivatives and their Application in Medicine

“…While studying the photochemical properties of pyridinium salts derived from purine bases, N-(2-aminopurin-6-yl) pyridinium chloride was synthesized applying the above mentioned methods but not used directly for the synthesis of O 6 -substituted guanines [76].…”