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Synthesis, and Electrochemical and Density Functional Studies of New Copper(II)‐ and Manganese(II) Oxicam Drugs. Redox Potentials and MOs Compatible with SOD‐like Activity and Unusual Six‐membered Rings of Water Molecules Bridging Complex Units
Author(s) -
Tamasi Gabriella,
Corsini Maddalena,
Cini Renzo
Publication year - 2014
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201300647
Subject(s) - chemistry , molecule , hydrogen bond , electrochemistry , amide , dimethylformamide , crystallography , copper , stereochemistry , medicinal chemistry , organic chemistry , electrode , solvent
Abstract The synthesis and rare structures of Mn II and Cu II complexes with OXI drugs ( oxicam , a family of non‐steroidal anti‐inflammatory drugs) are reported. On mixing Mn II acetate with piroxicam (H 2 PIR) pale yellow single crystals of trans , trans ‐[Mn II ( O ‐ N , N ‐DMF) 2 ( N , O ‐HPIR) 2 ], 1 , dimethylformamide (DMF), were obtained. The structure shows two HPIR – anions chelate through pyridyl nitrogen and amide oxygen, and two positions around the metal atom are occupied by the two DMF molecules. The Mn–O(amide, HPIR) vector is much shorter than the two other coordination vectors, a novelty for M II (L) 2 (HOXI) 2 molecules. Single crystals of trans , trans ‐[Cu II (H 2 O) 2 ( N , O ‐HTEN) 2 ]·4H 2 O·2DMF, 2 , (H 2 TEN, tenoxicam,) were obtained by long storage from DMF solutions of Cu II (HTEN) 2 during loading smart synthetic hydrogels. Compound 2 is the first example for M II (HOXI) 2 units, linked to H 2 O molecules ever reported, and extensive networks of H 2 O ··· OH 2 hydrogen bonds and Cu ··· OH 2 bonds that involve six member cycles of water molecules arranged as puckered rings bridging M II (HOXI) 2 entities. Infrared bands related to amide groups for HOXI – ligands are significantly influenced by the strength of M–O bonds in agreement with bond length trends. Electrochemical studies for Cu II (HTEN) 2 in tetrahydrofuran are in agreement with a SOD‐like scavenger activity at least for superoxide oxidation to molecular oxygen, E°(Cu II /Cu I , SCE) –0.31V. Furthermore, density functional investigation at the gas phase reproduces well the structure for trans , trans ‐[Mn II ( O ‐DMF) 2 ( N , O ‐HPIR) 2 ] sextuplet molecule and for trans , trans ‐[Cu II (H 2 O) 2 ( N , O ‐HTEN) 2 ] doublet molecule. Even a model of the {Cu II (HTEN) 2 (OH 2 ) ··· (H 2 O) 4 ··· (H 2 O)Cu II (HTEN) 2 } entity found for 2 is well reproduced by theory. The estimate stabilization energy brought about by the six water molecules ring between two Cu II (HTEN) 2 molecules is 69 kcal.