ABSTRACT
Three novel acetalophanes 1a-c have been designed, synthesized and characterized. The receptors 1b-c, featuring bulky anthracene groups, displayed significant selectivity for Fe3+ ions, resulting in a turn-off fluorescence mode in a DMF-buffer solution. Conversely, the non-steric probe 1a could serve as a versatile sensor for the simultaneous detection of Fe3+ and Cu2+ ions in MeOH-buffer solution. The sensing mechanism for the capability of 1a was demonstrated to be different, as evidenced by the addition of cyanide ions. The probes with Fe3+ exhibited a sensing mechanism that resulted in the deprotection of acetals to the corresponding starting materials, as confirmed by 1H NMR, IR spectra and TLC analysis. The attractive features of these practical and efficient sensors are selectivity, sensitivity (limit of detection = 0.15 µM by 1a, 0.16 µM by 1b and 0.14 µM by 1c), rapid response (less than 5 s). The on-site monitoring of various real samples, including well water, apricot, and green tea, proved to be successful for the quantitative and cost-effective detection of Fe3+. The method demonstrated good precision, even in the presence of other interfering materials.
ABSTRACT
Reaction of barbituric acid (BA), 1,3-dimethyl barbituric acid (DMBA) and 2-thiobarbituric acid (TBA) with cyanogen bromide and various aldehydes in presence of triethylamine afforded a new class of heterocyclic stable 5-alkyl and/or 5-aryl-1H, 1'H-spiro[furo[2,3-d]pyrimidine-6,5'-pyrimidine]2,2',4,4',6'(3H,3'H,5H)-pentaones which are dimeric forms of barbiturate (uracil and thiouracil derivatives) at 0 °C to ambient temperatures. Structure elucidation is proved by X-ray crystallography, (1)H NMR, (13)C NMR, FT-IR, CHN and mass analyses techniques. Mechanisms of the formations are discussed.
Subject(s)
Barbiturates/chemical synthesis , Pentanones/chemical synthesis , Pyrimidines/chemical synthesis , Spiro Compounds/chemical synthesis , Aldehydes/chemistry , Barbiturates/chemistry , Barbiturates/metabolism , Crystallography, X-Ray , Cyanogen Bromide/chemistry , Ethylamines/chemistry , Magnetic Resonance Spectroscopy , Molecular Structure , Pentanones/chemistry , Pyrimidines/chemistry , Spiro Compounds/chemistry , Thiobarbiturates/chemistryABSTRACT
In the title mol-ecule, C(15)H(18)N(4)O(6), the fused 2,3-dihydro-furan ring has an envelope conformation and the spiro pyrimidine ring has a half-chair conformation. In the crystal, short inter-molecular Oâ¯C contacts of 2.835â (4) and 2.868â (4)â Å between the carbonyl groups indicate the existence of electrostatic inter-actions, which link the mol-ecules into corrugated sheets parallel to the ab plane.