5,5'-[(2,4-Dichloro-phen-yl)methyl-ene]bis-(2,2-dimethyl-1,3-dioxane-4,6-dione).

The title compound, C(19)H(18)Cl(2)O(8), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 2,4-dichloro-benzaldehyde in ethanol. The two 1,3-dioxane rings exhibit boat conformations. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O and C-H⋯Cl hydrogen bonds, forming chains parallel to the a axis.

2,2-Dimethyl-5-(2,3,4-trimeth-oxy-benzyl-idene)-1,3-dioxane-4,6-dione.

The title compound, C(16)H(18)O(7), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 2,3,4-trimeth-oxy-benzaldehyde. The 1,3-dioxane ring is in a slightly distorted boat conformation. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

5-(3,4-Dimethyl-benzyl-idene)-2,2-dimethyl-1,3-dioxane-4,6-dione.

The title compound, C(15)H(16)O(4), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 3,4-dimethyl-benzaldehyde in ethanol. The 1,3-dioxane ring exhibits an envelope conformation. In the crystal, mol-ecules are linked by weak inter-molecular C-H⋯O hydrogen bonds, forming chains parallel to the b axis.

3-(2,4-Dichloro-benzyl-idene)-1,5-dioxa-spiro-[5.5]undecane-2,4-dione.

In the title mol-ecule, C(16)H(14)Cl(2)O(4), the 1,3-dioxane and cyclo-hexane rings exhibit distorted boat and chair conformations, respectively. In the crystal, a pair of weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into an inversion dimer.

Synthesis, characterization, crystal structure and DFT studies on 3-(1H-benzo[d][1,2,3]triazol-1-yl)-1-oxo-1-m-tolylpropan-2-yl-nicotinate.

3-(1H-Benzo[d][1,2,3]triazol-1-yl)-1-oxo-1-m-tolylpropan-2-yl-nicotinate (BOTN) has been synthesized and characterized by elemental analysis, IR, UV-vis and fluorescence spectroscopy. Its crystal structure has also been determined by X-ray single crystal diffraction. For BOTN, density functional theory (DFT) calculations of the structure and vibrational frequencies have been performed at B3LYP/6-311G** level. The comparisons between the experimental vibrational frequencies and the predicted data show that B3LYP/6-311G** method can simulate the IR of BOTN on the whole. Based on the vibration analysis, thermodynamic properties of BOTN have been calculated. The correlative equations between the thermodynamic properties and the temperatures have also been listed. The experimental UV-vis spectra present two peaks and theoretical UV-vis spectra obtained by TD-DFT method exhibit three peaks. The comparison between them suggests that the B3LYP/6-311G** method can only approximately simulate the UV-vis spectra of BOTN. The fluorescence determination reveals two emission bands at 423 and 489 nm, respectively.

3-(4-Fluoro-benzyl-idene)-1,5-dioxa-spiro-[5.5]undecane-2,4-dione.

In the title mol-ecule, C(16)H(15)FO(4), the fused 1,3-dioxane and cyclo-hexane rings exhibit a bath and a chair conformation, respectively. In the crystal, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers.

3-(4-Bromo-benzyl-idene)-1,5-dioxaspiro-[5.5]undecane-2,4-dione.

The title mol-ecule, C(16)H(15)BrO(4), was prepared by the reaction of (R)-2,4-dioxo-1,5-dioxaspiro-[5.5]undecane and 4-bromo-benzaldehyde with ethanol. The 1,3-dioxane ring exhibits a distorted boat and the fused cyclo-hexane ring exhibits a chair conformation.

2,2-Dimethyl-5-[(5-methyl-furan-2-yl)methyl-idene]-1,3-dioxane-4,6-dione.

The asymmetric unit of the title compound, C(12)H(12)O(5), contains two independent mol-ecules. In each, the 1,3-dioxane ring adopts an envelope conformation with the dimethyl-substituted C atom forming the flap. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

5-(4-Hy-droxy-benzyl-idene)-2,2-dimethyl-1,3-dioxane-4,6-dione.

The title compound, C(13)H(12)O(5), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 4-hy-droxy-benz-alde-hyde in ethanol. The 1,3-dioxane ring is in a distorted boat conformation. In the crystal, inversion dimers linked by pairs of O-H⋯O hydrogen bonds generate R(2) (2)(20) rings.

5-(4-Fluoro-benzyl-idene)-2,2-dimethyl-1,3-dioxane-4,6-dione.

The title compound, C(13)H(11)FO(4), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 4-fluoro-benz-alde-hyde in ethanol. The 1,3-dioxane ring adopts an envelope conformation. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

3-(4-Meth-oxy-benzyl-idene)-1,5-dioxa-spiro-[5.5]undecane-2,4-dione.

In the title mol-ecule, C(17)H(18)O(5), which was prepared by the reaction of (R)-1,5-dioxaspiro-[5.5]undecane-2,4-dione and 4-meth-oxy-benzaldehyde with ethanol, the 1,3-dioxane ring is in a distorted envelope conformation with the spiro C atom forming the flap. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

(E)-2,2-Dimethyl-5-(3-phenyl-allyl-idene)-1,3-dioxane-4,6-dione.

The title compound, C(15)H(14)O(4), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and (Z)-3-phenyl-acryl-aldehyde in ethanol. The dioxane ring is in a sofa conformation with the C atom bonded to the two methyl groups forming the flap. With the exception of the flap atom and the methyl group C atoms, all other non-H atoms are essentially planar, with an r.m.s. deviation of 0.067 (1) Å. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

2-(1H-Benzotriazol-1-yl)-1-(4-ethyl-benzo-yl)ethyl 2-chloro-benzoate.

In the crystal structure of the title compound, C(24)H(20)ClN(3)O(3), weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into chains extended along the a axis. The crystal studied was found to be an inversion twin.

(Z)-3-(3-Phenyl-allyl-idene)-1,5-dioxa-spiro-[5.5]undecane-2,4-dione.

In the title compound, C(18)H(18)O(4), the 1,3-dioxane ring adopts a distorted envelope conformation with the C atom common to the cyclo-hexane ring forming the flap. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds occur.

5-(2-Fluoro-benzyl-idene)-2,2-dimethyl-1,3-dioxane-4,6-dione.

The title compound, C(13)H(11)FO(4), was prepared by the reaction of 2,2-dimethyl-1,3-dioxane-4,6-dione and 2-fluoro-benzaldehyde in ethanol. In the crystal structure, mol-ecules are linked into chains by weak inter-molecular C-H⋯O hydrogen bonds.

2-Hydroxy-benzoic acid-purin-6-amine (3/1).

In the title 3:1 adduct, 3C(7)H(6)O(3)·C(5)H(5)N(5), an intra-molecular O-H⋯O hydrogen bond occurs in each of the three 2-hydroxy-benzoic acid mol-ecules. In the crystal, the components are linked by N-H⋯O and O-H⋯N hydrogen bonds.

3-(2-Furylmethyl-ene)-1,5-dioxaspiro-[5.5]undecane-2,4-dione.

In the title mol-ecule, C(14)H(14)O(5), the 1,3-dioxane ring is in an envelope conformation with the ring C atom common to the cyclo-hexane ring forming the flap. The other five atoms of the 1,3-dioxane ring are essentially planar [maximum deviation from the least-squares plane = 0.041 (3) Å] and form a dihedral angle of 13.75 (2)° with the furan ring. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds form extended chains along [101].

2-(1H-Benzotriazol-1-yl)-1-(3-methyl-benzo-yl)ethyl benzoate.

In the title mol-ecule, C(23)H(19)N(3)O(3), the dihedral angles between the mean plane of the benzotriazole ring system and the benzene and phenyl rings are 9.67 (9) and 86.08 (10)°, respectively. The dihedral angle between the benzene and phenyl rings is 85.89 (11)°. In the crystal structure, weak inter-molecular C-H⋯O hydrogen bonds link mol-ecules into chains along [010].

3-[(5-Methyl-furan-2-yl)methyl-ene]-1,5-dioxaspiro-[5.5]undecane-2,4-dione.

There are two crystallographically independent mol-ecules in the asymmetric unit of the title compound, C(15)H(16)O(5). In each, the 1,3-dioxane ring is in an envelope conformation with the C atom common to the cyclo-hexane ring forming the flap. The dihedral angles between the five essentially planar [maximum deviations from the least-squares planes of 0.049 (3) and 0.042 (3) Å] atoms of the 1,3-dioxane ring and the furan ring in the two mol-ecules are 7.15 (1) and 6.80 (1)°. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

2-(1H-Benzotriazol-1-yl)-1-(2-fluoro-benzo-yl)ethyl 4-methyl-benzoate.

In the crystal structure of the title compound, C(23)H(18)FN(3)O(3), inter-molecular C-H⋯N hydrogen bonds link the mol-ecules into chains extended along the c axis. The packing is further stabilized by weak C-H⋯O and C-H⋯F inter-actions. The F atom is disordered over two equally occupied 1- and 5-positions of the benzene ring.