Structure of N-[1'(9-adenyl)-β-D-ribofuranuronosyl]-L-phenylalanine water ethanol (1/0.5/0.25), C19H20N6O6.0.5H2O.0.25C2H6O

Abstract

Abstract. M r = 448.94, monoclinic, P21, a = 9.207 (1), b= 10.503 (2), c= 22.208 (3),/k, fl= 101.4 (1) °, V = 2105.2 (9) •3, Z = 4, D x = 1.416 gcm -3, 2(Cu Ka) = 1-5418 A, ~t = 9.3 cm -1, F(000) = 942, T= 293 K. Final R =0.053 for 4132 observed intensities. Both independent molecules in the asymmetric unit are zwitterions. One molecule has an extended conformation with the base anti and the sugar C(2') endo (2E); the other molecule has a closed conformation with the base syn and the sugar C(3') endo (3E).

Molecular Recognition of Protonated Cytosine Ribbons by Metal–Oxalato Frameworks

“…First, the inorganic–organic interaction in the (1H,9H-adeninium) 2 [Cu(ox) 2 (H 2 O) 2 ] compound is essentially maintained by two eight-member hydrogen-bonded R 2 2 (8) rings involving the N6H and N1H sites of the Watson–Crick face of the nucleobase as donors and oxalato-O atoms from O–Cu–O and O–C–O moieties as acceptors (Scheme ). Experimental and theoretical analysis on the interaction of DNA/RNA constituents and protein building blocks have shown that the last charge-assisted hydrogen bond motif exists in adeninium systems, but it is also a dominant association pattern of the protonated cytosine in both biological and artificial systems implying the N4H/N3H edge of the nucleobase and the carboxylate groups of the amino acid (Scheme ). Second, a perusal of the crystallographic information concerning high-dimensional aggregates of the cytosine nucleobase shows that the two previously reported homomeric self-assembling 1D patterns , for cytosinium cations are sustained by a single interaction via the exocyclic O-atom and one hydrogen atom of the N4 amino group, leaving the N4H and N3H sites as free hydrogen-bonding positions to afford forklike interactions with the carboxylate-O atoms.…”