Synthesis and structural characterization of platinum(II)-acyclovir complexes

Structural and Theoretical Evidence of the Depleted Proton Affinity of the N3-Atom in Acyclovir

“…The all-trans centrosymmetric anions (Figures 2 and A2) have symmetry-related pairs of O-aqua, N7-acv, and O-sulfate donor atoms featuring a rather typical elongated-octahedral Cu(II) coordination, type 4 + 2, with bond lengths of Cu-O(aqua) of 1.963(2) Å, of Cu-N7(acv) of 2.018(2) Å, and of Cu-O(sulfate) of 2.427(2) Å, respectively (Table A2). It seems clear that the, shortest strongly-bound Cu-O(aqua) favor the cooperation of each Cu-N7(acv) bond with an intra-molecular interligand (aqua)O1-H1B···O6(acv) interaction (2.615(3) Å, 157.3 • ) (Table A3), thus leading to the most common MBP of the acv ligand [2][3][4][5][6][7][8][9]12]. This fact imposes the coordination of O-sulfate atoms towards the apical/distal sites of the copper(II) surrounding.…”

“…An attempt to obtain the ternary complex Cu(II)-DEA-acv (DEA = diethanolamine) yielded a DEA-free greenish powder with a few well-shaped single crystals corresponding to the formula (H 3 O) 2 [Cu(acv) 2 (H 2 O) 2 (SO 4 ) 2 ]·2H 2 O (1, 100 K, monoclinic system, space group P2 1 /c, final R 1 = 0.045. Table A1) along with bluish Cu(OH) 2 .…”

“…An attempt to obtain the ternary complex Cu(II)-DEA-acv (DEA = diethanolamine) yielded a DEA-free greenish powder with a few well-shaped single crystals corresponding to the formula (H 3 O) 2 [Cu(acv) 2 (H 2 O) 2 (SO 4 ) 2 ]·2H 2 O (1, 100 K, monoclinic system, space group P2 1 /c, final R 1 = 0.045. Table A1) along with bluish Cu(OH) 2 . The all-trans centrosymmetric anions (Figures 2 and A2) have symmetry-related pairs of O-aqua, N7-acv, and O-sulfate donor atoms featuring a rather typical elongated-octahedral Cu(II) coordination, type 4 + 2, with bond lengths of Cu-O(aqua) of 1.963(2) Å, of Cu-N7(acv) of 2.018(2) Å, and of Cu-O(sulfate) of 2.427(2) Å, respectively (Table A2).…”

“…In addition, three (hydronium)O-H···O interactions stabilize the structure involving the O6, O(ol), and O(sulfate) atoms from three neighboring complex anions as acceptors, excluding the participation of O-water molecules within the intermolecular network (Table A4, Figures A3 and A4). The novel compound is closely related to the molecular compound all trans-[Cu(acv) 2 Figure 1. Formula of acyclovir and the numbering used in this work (see also Figure A1).…”

“…This acyclic guanine nucleoside analog has proved to bind nucleoside phosphorylases [1] as well as several metal ions. Structural knowledge on mixed-ligand metal-acv complexes (see selected reference [2][3][4][5][6][7][8][9][10][11][12]) supports a variety of metal binding patterns (MBPs) and interesting molecular recognition features. So far, the reported MBPs can be summarized as follows: (a) the formation of the M-N7 bond, with [2][3][4][5][6][7][8][9]12] or without [8,10] the cooperation of an intra-molecular interligand A-H···O6(acv) interaction (A=O or N acceptor); (b) the N7,O6-chelation mode [11]; (c) the µ 2 -N7,O(ol) (see Figure 1) bridging role [3]; and finally, (d) a multi-functional role featured by the µ 3 -N7,O6,O(e)+O(ol), which comprises the bridging, chelating, and tetradentate modes of acv [12].…”