Synthesis, structures and properties of self-assembling quaternary ammonium dansyl fluorescent tags for porous and non-porous surfaces.

A series of HO and/or EtOH soluble, self-assembling quaternary ammonium salts containing a dansyl (DNS) fluorescent moiety suitable for attachment to both porous ([DNS-NH-(CH)-NMe-R][X] (2; R = -Si(OMe), X = Cl) and non-porous (3a; R = -PO(OEt), 3b; -PO(Oi-Pr), 3c; -(PO(OH), X = Br), 4; ([DNS-NH-(CH)-NMe-(CH)-NH(CHPO(OEt)) ][Br], 5; R = -((CH)SCOCH, X = Cl), 6a; (R = -(CH)O(CH)CO(CH), n = 3, X = Br, 6b; n = 3, X = Cl, 6c; n = 3, X = I, 6d; n = 4, X = Br, 6e; n = 4, X = I, 6f; n = 6, X = Br, 6g; n = 6, X = Cl, 6h; n = 6, X = I), 7; (R = -CH-CH[double bond, length as m-dash]CH, X = Br) surfaces were prepared from the precursor dansyl amine (1; DNS-NH-(CH)-NMe). Compounds 1-7 were characterized by NMR (H, C, Si (2), P (3a-c, 4)) spectroscopy, HRMS, UV-Vis and fluorescence spectroscopy. Additional characterization of compounds 1 and 7 were carried out by X-ray structure determinations. Physical attachment of compound 2 to cotton surfaces after immersion in solutions containing fluorescent dyes was verified by exposure to UV light and by complexation with bromo-phenol blue that rendered the surfaces visibly blue in colour. Phosphorus containing dansyl fluorescent dye, 3c, was attached to a stainless steel surface by exposure to an aqueous solution containing this dye, resulting in the formation of a self-assembled fluorescent monolayer. UV cure of plastic surfaces (polypropylene, silicon medical tubing) coated with compound 6a resulted in the covalent attachment of the dyes.