Spacer-chromoionophores - polymethine dye substituted aza-crown ethers with increased complexation ability

Abstract

Chromoionophores are crown ether derivatives, which contain a chromophoric group [1][2][3]. These functional dyes are of a great interest for analytical applications [4,5], especially in medical diagnostics and therapy. A great number of chromo-and also fluoroionophores, starting from aldehydes of N-phenyl-aza-15-crown-5 or N-phenyl-aza-18-crown-6 are described in the literature [6 -11]. Substitution of the aminic H-atom in aza-crowns leads to nitrogen-pivot lariat crowns, and it was shown that alkyl groups increase the binding strength of the metal complexes [12 -14]. The present paper deals with the synthesis of deeply colored polymethine crown ether derivatives and the influence of the electron acceptor properties of the side chain on the complexation, depending upon conjugation of the chromophore with the nitrogen of the aza-crowns. Abstract. Aromatic aldehyde derivatives of N-phenyl-aza-15-crown-5 2, N-phenyl-aza-18-crown-6 8, and benzo-15-crown-5 10 are condensed with malononitrile and 2-amino-1,1,3-tricyano-1-propene to give light yellow to orange colored crown ether derivatives 4, 5a, 9a, 11, and 12. 5a and 9a were acylated with ethyl chloroformate to give the magenta colored dyes 5b and 9b, respectively. By condensation of N-(4-nitrosophenyl)-aza-15-crown-5 3 with 2-amino-1,1,3-tricyano-1-propene the magenta dye 6a is obtained. Acylation of 6a with ethyl chloroformiate leads to the deep blue colored dye 6b. In these derivatives the nitrogen or oxygen atoms of the crown ethers are part of the chro-mophoric system and binding properties are affected. Further chromophoric derivatives of aza-crown ethers are stu-died in which these are separated from the chromophoric moiety by a spacer. N-(ω-chloroalkyl)-N-alkylanilines 14a -c were attached to aza-15-crown-5 13a and aza-18-crown-6 13b to yield the spacer crown ether derivatives 15a -c and 16a -c, respectively. The formylated spacer crown ether derivatives 17a -c and 18b were condensed with 2-amino-1,1,3-tricyano-1-propene to give the orange spacer-chromoionophores 19a -c and 20. In these crown ether derivatives the extended conjugation is interrupted by the spacer and good binding properties are obtained. The complex formation constants of the crown ether derivatives with Na + and K + are determined using 1 H NMR spectroscopy. dimeric malononitrile (2-amino-1,1,3-tricyanopropene), respectively, is a Knoevenagel condensation which occurs under mild conditions using piperidine as catalyst. The yellow colored chromoionophores 4 and 5a, showing UV/Vis absorption maxima at about λ max = 430 nm, are obtained with a quite good yield.13-(4-Nitrosophenyl)-1,4,7,10-tetraoxa-13-azacyclopentadecane 3 was as well prepared according to Dix and Vögtle [6]. With the dimeric malononitrile it afforded with good yield the magenta colored dye 6a (λ max = 524 nm, CH 3 CN).N-Phenyl-aza-18-crown-6 7 was synthesized according to Dix und Vögtle [6], and the corresponding aldehyde 8 similarly to the crown ether aldehyde 2 prepared by Vilsmeier formylation. Formation of side produc...

Reaction of bromomalononitrile with 2-amino-4-arylbuta-1,3-diene-1,1,3-tricarbonitriles

“…Structurally related alkylidene and arylmethylidene derivatives of malononitrile dimer, 2-amino-4-arylbuta-1,3-diene-1,1,3-tricarbonitriles Ia-Ic, are usually prepared by Knoevenagel condensation of malononitrile dimer with carbonyl compounds [3][4][5][6][7][8][9][10][11][12][13]. Although these compounds have long been known, their synthetic potential has been explored poorly, and only a few publications on their reactivity are available, specifically on Michael addition at the activated double bond.…”