catena-Poly[[[triaquacobalt(II)]-μ-10-methylphenothiazine-3,7-dicarboxylato] monohydrate]

The polymeric title compound, {[Co(C15H9NO4S)(H2O)3]·H2O}n, consists of chains along [001] made up from Co2+ ions bridged by 10-methylphenothiazine-3,7-dicarboxylate anions. The Co2+ ion, coordinated by three O atoms from two different carboxylate groups and three water molecules, displays a distorted octahedral environment. In the crystal, π–π interchain interactions, with centroid–centroid distances of 3.656 (2) and 3.669 (2) Å between the benzene rings of the ligands, assemble the chains into sheets parallel to (100). O—H⋯O hydrogen-bonding interactions between the coordinating water molecules and carboxylate O atoms link the sheets into a three-dimensional network.

The polymeric title compound, {[Co(C 15 H 9 NO 4 S)(H 2 O) 3 ]Á-H 2 O} n , consists of chains along [001] made up from Co 2+ ions bridged by 10-methylphenothiazine-3,7-dicarboxylate anions. The Co 2+ ion, coordinated by three O atoms from two different carboxylate groups and three water molecules, displays a distorted octahedral environment. In the crystal, interchain interactions, with centroid-centroid distances of 3.656 (2) and 3.669 (2) Å between the benzene rings of the ligands, assemble the chains into sheets parallel to (100). O-HÁ Á ÁO hydrogen-bonding interactions between the coordinating water molecules and carboxylate O atoms link the sheets into a three-dimensional network.
Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: SHELXTL. Phenothiazine, an intriguing type of biologically and pharmaceutically active heterocyclic compound well known as a pharmacophore in tranquilizers, antituberculosis agents, anti-tumor agents, bactericides, etc. (Albery et al., 1979;Tsakovska & Pajeva, 2006), is now widely studied as an electron donor component and electrically conducting chargetransfer composite on account of its unique electro-optic properties in materials science (Chakraborty et al., 2005;Cho et al., 2006;Park et al., 2008). Previous studies involving this compound had more emphasis on the large π-electron conjugated system (Krämer et al., 2001;Zhang et al., 2007); however, less work is reported on the construction of metalorganic frameworks using it as a building block. Here we employed the 10-methyl-10H-phenothiazine-3,7-dicarboxylate (MPTD) anion as a ligand to crystallize the title complex.
The title compound, {[Co(C 15 H 9 NO 4 S)(H 2 O) 3 ] . H 2 O}, consists of a three-dimensional supramolecular network built up from coordination bonds, hydrogen bonds, and π-π interactions. As shown in Fig. 1, the Co 2+ ion has a slightly distorted octahedral coordination environment formed by three O atoms from two different carboxylate ligands and three O atoms from three coordinated water molecules. Each MPTD ligand bridges two Co atoms via two carboxylate groups in a monodentate and a bidentate coordination mode into a one-dimensional zigzag chain parallel to [001]. These chains are assembled in an antiparallel manner into two-dimensional sheets parallel (100) based on strong interchain π-π interactions between the ligands [centroid-centroid distance = 3.656, 3.669 Å]. The sheets are further connected to form a three-dimensional supramolecular network ( Fig. 2

) via interlayer O-H···O hydrogen bond interactions. A PLATON
calculation (Spek, 2009) shows that the structure has 13.6% solvent accessible voids when the coordinated and lattice water molecules are neglected. The resulting framework structure contains channels with approximate dimensions of 2.9×4.9 Å 2 and 1.9×1.9 Å 2 along [010] and [001], respectively. All the lattice water molecules and the coordinating water molecules are situated in these channels and are involved in the above extensive interlayer and intralayer H-bonding.

Experimental
The educt 10-methyl-10H-phenothiazine-3,7-dicarboxylic acid used to construct the title compound {[Co(C 15 H 9 NO 4 S) (H 2 O) 3 ] . H 2 O} was prepared by oxidation of 10-methyl-10H-phenothiazine-3,7-dicarbaldehyde using silver nitrate as oxidant in an alkaline medium. 10-Methyl-10H-phenothiazine-3,7-dicarbaldehyde (0.6417 g, 2.38 mmol) (Cho et al., 2006) was dissolved in 35 ml solution of KOH (10.0 g, 0.178 mol), then a 5 ml solution of AgNO 3 (1.3 g, 7.65 mmol) was added slowly. The mixture was filtered after heating at 103 K overnight, then HCl (2 M) was added to the filtrate until the pH value reached 1~2, during which a large amount of precipitate formed. The precipitate was filtered off, washed with distilled water, re-dissolved in KOH solution, and again acidified to pH 1~2. The final acidification product was obtained by filtration and dried in vacuo (yield 0.4323 g, 60.3% 0.2 mmol) and 10-methyl-10H-phenothiazine-3,7-dicarboxylic acid (15.6 mg, 0.05 mmol) in a mixed solvent of ethanol and H 2 O (8 ml, volume ratio 1:4) at 393 K for 86 h and finally cooled to room temperature. The resulting products were filtered off, washed thoroughly with distilled water and dried in air at room temperature. The yield was 38.7 mg (45%).

Refinement
All the H atoms were fixed geometrically and treated as riding with C-H = 0.96 Å, O-H = 0.85 Å and with U iso (H) = 1.2U eq (C) or 1.5U eq (C, O) for methyl and water H atoms.

catena-Poly[[[triaquacobalt(II)]-µ-10-methylphenothiazine-3,7-dicarboxylato] monohydrate]
Crystal data Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.