General Papers ARKIVOC 2007 (xiii) 87-104
Synthesis and fluorescent properties of new derivatives of 4-amino-7-nitrobenzofurazan
Marioara Bem,a Florin Badea,b Constantin Draghici,c Miron T. Caproiu,c Marilena Vasilescu,a Mariana Voicescu,a Adrian Beteringhe,a Agneta Caragheorgheopol,a Maria Maganu,c Titus Constantinescu,a and Alexandru T. Balaband*
a Roumanian Academy, “Ilie Murgulescu” Institute of Physical Chemistry, Laboratory of Supramolecular Chemistry and Interphase Processes, Splaiul Independentei 202, 060021, Roumania E-mail:
[email protected] b Politehnica University Bucharest, Department of Organic Chemistry, Splaiul Independentei 313, Bucharest, Roumania c Roumanian Academy, “C. D. Nenitzescu” Institute of Organic Chemistry, NMR Department, Splaiul Independentei 202 B, Bucharest, Roumania d Texas A&M University at Galveston, 5007 Ave. U, Galveston, TX, 77553-1675, USA E-mail:
[email protected]
Abstract
The following new compounds were obtained by reacting 4-chloro-7-nitrobenzofurazan (NBD- Cl, 1) with five primary amines: 3b with a benzo-crown ether 18C6; 3c with an N-(a-naphthyl)ethylenediamine group; 3d, with a 2,2,6,6-tetramethylpiperidin-N-oxyl group; 3e, with an apicolyl group; and 3f, derived from tris(hydroxymethyl)aminomethanol. Also, from the reaction of 1 with N-methylhydroxylamine an N-hydroxy-N-methyl-NBD derivative (3g) was prepared. All these six new NBD derivatives 3b-g were studied (in comparison with the known compound 3a prepared from 1 and aniline) for their physical and chemical properties, with special emphasis on hydrophobicity, UV-Vis, fluorescence, using also structural studies trough QSPR.
Keywords: 4-Amino-7-nitrobenzoxadiazole derivatives, UV-Vis, fluorescence, EPR, hydrophobicity, QSPR
Introduction
Many 4-substituted-7-nitro-2,1,3-benzoxadiazoles (NBD derivatives) have a strong fluorescence which has led to their use in bioanalytical chemistry.1-23 Their benzoxadiazole ring system also been called 3,4-benzo-1,2,5-oxadiazole or benzofurazan. The usual synthesis is based on the
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