Bis(guanidinium) naphthalene-1,5-disulfonate–18-crown-6 (1/1)

In the crystal of the title compound, 2CH6N3 +·C10H6O6S2 2−·C12H24O6, the 1,5-naphthnalenedisulfonate anion and the 18-crown-6 molecule lie across inversion centers. The guanidinium cation links with the 1,5-naphthnalenedisulfonate anion and 18-crown-6 molecule via N—H⋯O hydrogen bonds.

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL. extraction, isotopeseparation, bionice, host-guest chemistry and supramolecular chemistry (Clark et al., 1998). Several 18-crown-6 clathrates were discovered to be dielectric-ferroelectric materials (Fu et al., 2011), hence we design the title compound to find new hydrogen bonding type dielectric materials. Dielectric-ferroelectric materials, comprising organic ligands, metal-organic coordination compounds and organic-inorganic hybrids almost show dielectric constant of temperature-dependent (Fu et al., 2009;Zhang et al., 2010;Zhang et al., 2008;Ye et al., 2006). Unfortunately, the dielectric constant of the title compound as a function of temperature indicates that the permittivity is basically temperature-independent, below the melting point (395k-396k) of the compound, we have found that title compound has no dielectric disuniform from 80 K to 405 K. Herein we descibe the crystal structure of this compound.
At home temperature (25°C), the single-crystal X-ray diffraction reveals that the structure get crystallization in the triclinic system, space group P-1 and the asymmetric unit of the title compound consists of a guanidinium cation, a 1,5naphthalenedisulfonate anion and a 18-crown-6 molecule ( Fig. 1). The three -NH 2 + groups form guanidinium interact with three O atoms of one crown ether molecule and other three O atoms from two 1,5-naphthalenedisulfonate anions through six N-H···O hydraogen bonds (Table 1), composing a three-dimensional crystal structure (Fig. 2).

Experimental
The 1,5-naphthalene disulfonic acid (1.15 g, 4 mmol) and guanidinium tetrafluoroborate (1.17 g, 8 mmol) were dissolved in 30 ml water and the solution was combined with methanol solution of dibenzo-18-crown-6 (1.44 g 4 mmol). The mixture solution was stirred for 30 min to reaction fully and good quality blocky single crystals were obtained by slow evaporation of the filtrate after two weeks (the chemical yield 61%).

Refinement
Amino H atoms were located in a difference Fourier map and refined isotropically. Other H atoms were placed in geometrically idealized positions nd constrained to ride on their parent atoms with C-H = 0.93-0.97 Å, U iso (H) = 1.2U iso (C).  The molecular structure of the title compound, with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

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.