Photocurable acrylate epoxy/ZnO-Ag nanocomposite coating: fabrication, mechanical and antibacterial properties.

In this study, a UV-curable acrylate epoxy nanocomposite coating has been prepared by incorporation of ZnO-Ag hybrid nanoparticles. For this purpose, firstly ZnO-Ag hybrid nanoparticles were fabricated by a seed-mediated growth method. Then, these ZnO-Ag hybrid nanoparticles (2 wt%) were added into the UV-curable acrylate resin matrices. The photocuring process of nanocomposite was evaluated by various factors, such as the conversion of acrylate double bonds, pendulum hardness and gel fraction. Under the 4.8 s UV-exposure time for full crosslinking, the obtained data indicated that incorporation of ZnO-Ag nanohybrids into the coating matrix changed the crosslinking process of coating significantly. A mechanical teat indicated that the presence of nanohybrids in photocurable coating matrix enhanced its abrasion resistance from 98.7 to 131.6 L per mil (33.3%). The antibacterial test against E. coli over 7 h indicated that E. coli bacteria were killed totally by nanocomposite coating, whereas it was 2.6 × 104 CFU mL-1 for the neat coating without nanoparticles.

DFT study on some polythiophenes containing benzo[d]thiazole and benzo[d]oxazole: structure and band gap.

The content of this paper focuses/shed light on the effects of X (X = S in P1 and X = O in P2) in C11H7NSX and R (R = H in P3, R = OCH3 in P4, and R = Cl in P5) in C18H9ON2S2-R on structural features and band gaps of the polythiophenes containing benzo[d]thiazole and benzo[d]oxazole by the Density Function Theory (DFT) method/calculation. The structural features including the electronic structure lattice constant (a), shape, total energy (Etot) per cell, and link length (r), are measured via band gap (Eg) prediction with the package of country density (PDOS) and total country density (DOS) of material studio software. The results obtained showed that the link angle and the link length between atoms were not changed significantly while the Etot was decreased from Etot = - 1904 eV (in P1) to Etot = - 2548 eV (in P2) when replacing O with S; and the Etot of P3 was decreased from Etot = - 3348 eV (in P3) when replacing OCH3, Cl on H of P3 corresponding to Etot = - 3575 eV (P4), - 4264 eV (P5). Similarly, when replacing O in P1 with - S to form P2, the Eg of P1 was dropped from Eg = 0.621 eV to Eg = 0.239 eV for P2. The Eg of P3, P4, and P5 is Eg = 0.006 eV, 0.064 eV, and 0.0645 eV, respectively. When a benzo[d]thiazole was added in P1 (changing into P3), the Eg was extremely strongly decreased, nearly 100 times (from Eg = 0.621 eV to Eg = 0.006 eV). The obtained results serve as a basis for future experimental work and used to fabricate smart electronic device.

Crystal structure of potassium hydrogen bis-((E)-2-{4-[3-(thio-phen-3-yl)acrylo-yl]phen-oxy}acetate).

The synthesis and spectroscopic data of (E)-2-{4-[3-(thio-phen-3-yl)acrylo-yl]phen-oxy}acetic acid are described. Crystallization from an ethanol-water mixture resulted in the title compound, C30H23KO8S2 or [K(C15H11O4S)(C15H12O4S)] n , containing one mol-ecule of the acid and one mol-ecule of the potassium salt in the asymmetric unit. Both mol-ecules share the H atom between their carboxyl groups and a potassium ion. The C=C bonds display an E configuration. The thio-phene and phenyl rings in the two mol-ecules are inclined by 43.3 (2) and 22.7 (2)°. The potassium ion is octa-hedrally coordinated by six O atoms. This distorted octa-hedron shares on opposite sides two oxygen atoms with inversion-related octa-hedra, resulting in chains of octa-hedra running in the [010] direction, which form ladder-like chains by C-H⋯π inter-actions. A Hirshfeld surface analysis indicates that the highest contributions to the surface contacts arise from inter-actions in which H atoms are involved, with the most important contribution being from H⋯H (31.6 and 31.9% for the two mol-ecules) inter-actions.

Effect of doped H, Br, Cu, Kr, Ge, As and Fe on structural features and bandgap of poly C13H8OS-X: a DFT calculation.

Structural features such as the shape, the lattice constant, the bond length, the total energy per cell, and the energy bandgap (Eg) of C13H8OS-X are studied by the calculating Partial Density Of States (PDOS), and DOS package of the Material Studio (MS) software. Calculations show that the bond length and the bond angle between atoms insignificant change as 1.316 Å to 1.514 Å for C-C, 1.211 Å for C-O, 1.077 Å to 1.105 Å for C-H; bond angle of round one changes from 118.883° to 121.107° for C-C-C, from 117.199° to 122.635° for H-C-C, from 119.554° to 123.147° for C-C-O and from 109.956° to 117.537° for C-C-H. When C13H8OS-X doped in the order of -Br, -Cu, -Kr, -Ge, -As, and -Fe then bond lengths, bond angles between atoms have a nearly constant value. Particularly for links C-X, there is a huge change in value, respectively 1.876, 1.909, 10.675, 2.025, 2.016, 2.014 Å; the total energy change from Etot = -121,794 eV to Etot = -202,859 eV, and the energy band gap decreases from Eg = 2.001 eV to Eg = 0.915 eV. The obtained results are useful and serve as a basis for future experimental research.

Synthesis and structure of (E)-N-(4-meth-oxy-phen-yl)-2-[4-(3-oxo-3-phenyl-prop-1-en-1-yl)phen-oxy]acetamide.

The title compound N-(4-meth-oxy-phen-yl)-2-[4-(3-oxo-3-phenyl-prop-1-en-1-yl)phen-oxy]acetamide, C24H21NO4, was prepared from reaction of N-(4-meth-oxy-phen-yl)-2-chloro-acetamide and (E)-3-(4-hy-droxy-phen-yl)-1-phenyl-prop-2-en-1-one, which was obtained from the reaction of 4-hy-droxy-benzaldehyde and aceto-phenone. The structure of the title compound was determined by IR, 1H-NMR, 13C-NMR and HR-MS spectroscopic data and further characterized by single-crystal X-ray diffraction. The asymmetric unit contains four mol-ecules, each displaying an E-configuration of the C=C bond. The dihedral angle between the phenyl rings in each mol-ecule varies between 14.9 (2) and 45.8 (2)°. In the crystal, C-H⋯O hydrogen-bonding inter-actions link the mol-ecules into chains running along the [001] direction. In addition, C-H⋯π inter-actions further stabilize the crystal packing. A Hirshfeld analysis indicates that the most important contributions to the surface contacts are from H⋯H (43.6%), C⋯H/H⋯C (32.1%) and O⋯H/H⋯O (18.1%) inter-actions.

DFT Prediction of Factors Affecting the Structural Characteristics, the Transition Temperature and the Electronic Density of Some New Conjugated Polymers.

Conjugated polymers are promising materials for various cutting-edge technologies, especially for organic conducting materials and in the energy field. In this work, we have synthesized a new conjugated polymer and investigated the effect of distance between bond layers, side-chain functional groups (H, Br, OH, OCH3 and OC2H5) on structural characteristics, phase transition temperature (T), and electrical structure of C13H8OS using Density Functional Theory (DFT). The structural characteristics were determined by the shape, network constant (a, b and c), bond length (C-C, C-H, C-O, C-S, C-Br and O-H), phase transition temperatures, and the total energy (Etot) on a base cell. Our finding shows that the increase of layer thickness (h) of C13H8OS-H has a negligible effect on the transition temperature, while the energy bandgap (Eg) increases from 1.646 eV to 1.675 eV. The calculation of bond length with different side chain groups was carried out for which C13H8OS-H has C-H = 1.09 Å; C13H8OS-Br has C-Br = 1.93 Å; C13H8OS-OH has C-O = 1.36 Å, O-H = 0.78 Å; C13H8OS-OCH3 has C-O = 1.44 Å, O-H =1.10 Å; C13H8OS-OC2H5 has C-O = 1.45 Å, C-C = 1.51Å, C-H = 1.10 Å. The transition temperature (T) for C13H8OS-H was 500 K < T < 562 K; C13H8OS-Br was 442 K < T < 512 K; C13H8OS-OH was 487 K < T < 543 K; C13H8OS-OCH3 was 492 K < T < 558 K; and C13H8OS-OC2H5 was 492 K < T < 572 K. The energy bandgap (Eg) of Br is of Eg = 1.621 eV, the doping of side chain groups H, OH, OCH3, and OC2H5, leads to an increase of Eg from 1.621 eV to 1.646, 1.697, 1.920, and 2.04 eV, respectively.

Polyoxymethylene/silica/polylactic acid-grafted polyethylene glycol nanocomposites: structure, morphology, and mechanical properties and ozone and UV durability.

Polyoxymethylene (POM) is a semicrystalline thermoplastic that displays high tensile strength, thermal stability, and chemical durability. However, its widespread application is limited by its low elongation at break and thermal durability. In the present study, nanosilica (NS) and polylactic acid-grafted polyethylene glycol (PELA) were used as enhancement additives to improve the performance of POM homopolymer. Specifically, the POM/PELA/NS nanocomposites with a fixed NS content and varying PELA contents were prepared by a melt mixing method. The influence of the additives on the processability, and dynamic thermo-mechanical and tensile properties of the nanocomposites was evaluated by comparing the torque, mixing energy at melt state, storage modulus, shear stress, loss modulus, tan δ, tensile strength, elongation at break and thermal degradation of the nanocomposites. The results showed that the combined addition of NS and PELA enhanced the thermal stability, tensile strength, elongation at break and chemical stability of the POM/PELA/NS nanocomposites owing to the good compatibility between PELA and the POM matrix. Furthermore, the morphology, and UV and ozone durability of POM and the nanocomposites were assessed and discussed.

Glucose Uptake Stimulatory and PTP1B Inhibitory Activities of Pimarane Diterpenes from Orthosiphon stamineus Benth.

Seven pimarane diterpenes (1-7) were isolated from Orthosiphon stamineus Benth. by assay-guided isolation. All of the isolates possessed a 2-deoxy-2-((7-nitro-2,1,3-benzoxadiazol-4-yl)amino)-d-glucose uptake effect in 3T3-L1 adipocytes at concentrations of 5 and 10 µM. Most of them showed potent inhibition against protein tyrosine phosphatase 1B with IC50 values ranging from 0.33 to 9.84 µM. In the kinetic study, all inhibition types were exposed for the examined potencies, including mixed-competitive (1), non-competitives (3 and 5), competitive (6), and uncompetitive (7). The results suggested that O. stamineus and its pimarane diterpenes might exert the hypoglycemic effect via the insulin signaling pathway targeting inhibition of protein tyrosine phosphatase 1B (PTP1B) activity.

Synthesis, crystal structure and Hirshfeld surface analysis of diethyl 2,6-dimethyl-4-(thio-phen-3-yl)-1,4-di-hydro-pyridine-3,5-di-carboxyl-ate.

In the title compound, C17H21NO4S, the 1,4-di-hydro-pyridine ring has an envelope conformation with the Csp 3 atom at the flap. The thio-phene ring is nearly perpendicular to the best plane through the 1,4-di-hydro-pyridine ring, the dihedral angle being 82.19 (13)°. In the crystal, chains running along the b-axis direction are formed through N-H⋯O inter-actions between the 1,4-di-hydro-pyridine N atom and one of the O atoms of the ester groups. Neighbouring chains are linked by C-H⋯O and C-H⋯π inter-actions. A Hirshfeld surface analysis shows that the most prominent contributuion to the surface contacts are H⋯H contacts (55.1%).

Synthesis, crystal structure and Hirshfeld surface analysis of 4-[3-(4-hy-droxy-phen-yl)-4,5-di-hydro-1H-pyrazol-5-yl]-2-meth-oxy-phenol monohydrate.

In the title pyrazoline derivative, C16H16N2O3·H2O, the pyrazoline ring has an envelope conformation with the substituted sp 2 C atom on the flap. The pyrazoline ring makes angles of 86.73 (12) and 13.44 (12)° with the tris-ubstituted and disubstituted benzene rings, respectively. In the crystal structure, the mol-ecules are connected into chains running in the b-axis direction by O-H⋯N hydrogen bonding. Parallel chains inter-act through N-H⋯O hydrogen bonds and π-π stacking of the tris-ubstituted phenyl rings. The major contribution to the surface contacts are H⋯H contacts (44.3%) as concluded from a Hirshfeld surface analysis.

Synthesis and redetermination of the crystal structure of salicyl-aldehyde N(4)-morpholino-thio-semi-carbazone.

The structure of the title compound (systematic name: N-{[(2-hy-droxy-phen-yl)methyl-idene]amino}-morpholine-4-carbo-thio-amide), C12H15N3O2S, was prev-iously determined (Koo et al., 1977 ▸) using multiple-film equi-inclination Weissenberg data, but has been redetermined with higher precision to explore its conformation and the hydrogen-bonding patterns and supra-molecular inter-actions. The mol-ecular structure shows intra-molecular O-H⋯N and C-H⋯S inter-actions. The configuration of the C=N bond is E. The mol-ecule is slightly twisted about the central N-N bond. The best planes through the phenyl ring and the morpholino ring make an angle of 43.44 (17)°. In the crystal, the mol-ecules are connected into chains by N-H⋯O and C-H⋯O hydrogen bonds, which combine to generate sheets lying parallel to (002). The most prominent contribution to the surface contacts are H⋯H contacts (51.6%), as concluded from a Hirshfeld surface analysis.

Crystal structure of two N'-(1-phenyl-benzyl-idene)-2-(thio-phen-3-yl)acetohydrazides.

The synthesis, spectroscopic data, crystal and mol-ecular structures of two N'-(1-phenyl-benzyl-idene)-2-(thio-phen-3-yl)acetohydrazides, namely N'-[1-(4-hy-droxy-phen-yl)benzyl-idene]-2-(thio-phen-3-yl)acetohydrazide, C13H10N2O2S, (3a), and N'-[1-(4-meth-oxy-phen-yl)benzyl-idene]-2-(thio-phen-3-yl)acetohydrazide, C14H14N2O2S, (3b), are described. Both compounds differ in the substituent at the para position of the phenyl ring: -OH for (3a) and -OCH3 for (3b). In (3a), the thio-phene ring is disordered over two orientations with occupancies of 0.762 (3) and 0.238 (3). The configuration about the C=N bond is E. The thio-phene and phenyl rings are inclined by 84.0 (3) and 87.0 (9)° for the major- and minor-occupancy disorder components in (3a), and by 85.89 (12)° in (3b). Although these dihedral angles are similar, the conformation of the linker between the two rings is different [the C-C-C-N torsion angle is -ac for (3a) and -sc for (3b), while the C6-C7-N9-N10 torsion angle is +ap for (3a) and -sp for (3b)]. A common feature in the crystal packing of (3a) and (3b) is the presence of N-H⋯O hydrogen bonds, resulting in the formation of chains of mol-ecules running along the b-axis direction in the case of (3a), or inversion dimers for (3b). The most prominent contributions to the surface contacts are those in which H atoms are involved, as confirmed by an analysis of the Hirshfeld surface.

Some chalcones derived from thio-phene-3-carbaldehyde: synthesis and crystal structures.

The synthesis, spectroscopic data and crystal and mol-ecular structures of four 3-(3-phenyl-prop-1-ene-3-one-1-yl)thio-phene derivatives, namely 1-(4-hydroxy-phen-yl)-3-(thio-phen-3-yl)prop-1-en-3-one, C13H10O2S, (1), 1-(4-meth-oxy-phen-yl)-3-(thio-phen-3-yl)prop-1-en-3-one, C14H12O2S, (2), 1-(4-eth-oxy-phen-yl)-3-(thio-phen-3-yl)prop-1-en-3-one, C15H14O2S, (3), and 1-(4--bromophen-yl)-3-(thio-phen-3-yl)prop-1-en-3-one, C13H9BrOS, (4), are described. The four chalcones have been synthesized by reaction of thio-phene-3-carbaldehyde with an aceto-phenone derivative in an absolute ethanol solution containing potassium hydroxide, and differ in the substituent at the para position of the phenyl ring: -OH for 1, -OCH3 for 2, -OCH2CH3 for 3 and -Br for 4. The thio-phene ring in 4 was found to be disordered over two orientations with occupancies 0.702 (4) and 0.298 (4). The configuration about the C=C bond is E. The thio-phene and phenyl rings are inclined by 4.73 (12) for 1, 12.36 (11) for 2, 17.44 (11) for 3 and 46.1 (6) and 48.6 (6)° for 4, indicating that the -OH derivative is almost planar and the -Br derivative deviates the most from planarity. However, the substituent has no real influence on the bond distances in the α,ß-unsaturated carbonyl moiety. The mol-ecular packing of 1 features chain formation in the a-axis direction by O-H⋯O contacts. In the case of 2 and 3, the packing is characterized by dimer formation through C-H⋯O inter-actions. In addition, C-H⋯π(thio-phene) inter-actions in 2 and C-H⋯S(thio-phene) inter-actions in 3 contribute to the three-dimensional architecture. The presence of C-H⋯π(thio-phene) contacts in the crystal of 4 results in chain formation in the c-axis direction. The Hirshfeld surface analysis shows that for all four derivatives, the highest contribution to surface contacts arises from contacts in which H atoms are involved.

Synthesis, structure and in vitro cytotoxicity testing of some 1,3,4-oxadiazoline derivatives from 2-hydroxy-5-iodobenzoic acid.

The syntheses of nine new 5-iodosalicylic acid-based 1,3,4-oxadiazoline derivatives starting from methyl salicylate are described. These compounds are 2-[4-acetyl-5-methyl-5-(3-nitrophenyl)-4,5-dihydro-1,3,4-oxadiazol-2-yl]-4-iodophenyl acetate (6a), 2-[4-acetyl-5-methyl-5-(4-nitrophenyl)-4,5-dihydro-1,3,4-oxadiazol-2-yl]-4-iodophenyl acetate (6b), 2-(4-acetyl-5-methyl-5-phenyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)-4-iodophenyl acetate, C19H17IN2O4 (6c), 2-[4-acetyl-5-(4-fluorophenyl)-5-methyl-4,5-dihydro-1,3,4-oxadiazol-2-yl]-4-iodophenyl acetate, C19H16FIN2O4 (6d), 2-[4-acetyl-5-(4-chlorophenyl)-5-methyl-4,5-dihydro-1,3,4-oxadiazol-2-yl]-4-iodophenyl acetate, C19H16ClIN2O4 (6e), 2-[4-acetyl-5-(3-bromophenyl)-5-methyl-4,5-dihydro-1,3,4-oxadiazol-2-yl]-4-iodophenyl acetate (6f), 2-[4-acetyl-5-(4-bromophenyl)-5-methyl-4,5-dihydro-1,3,4-oxadiazol-2-yl]-4-iodophenyl acetate (6g), 2-[4-acetyl-5-methyl-5-(4-methylphenyl)-4,5-dihydro-1,3,4-oxadiazol-2-yl]-4-iodophenyl acetate (6h) and 2-[5-(4-acetamidophenyl)-4-acetyl-5-methyl-4,5-dihydro-1,3,4-oxadiazol-2-yl]-4-iodophenyl acetate (6i). The compounds were characterized by mass, 1H NMR and 13C NMR spectroscopies. Single-crystal X-ray diffraction studies were also carried out for 6c, 6d and 6e. Compounds 6c and 6d are isomorphous, with the 1,3,4-oxadiazoline ring having an envelope conformation, where the disubstituted C atom is the flap. The packing is determined by C-H...O, C-H...π and I...π interactions. For 6e, the 1,3,4-oxadiazoline ring is almost planar. In the packing, Cl...π interactions are observed, while the I atom is not involved in short interactions. Compounds 6d, 6e, 6f and 6h show good inhibiting abilities on the human cancer cell lines KB and Hep-G2, with IC50 values of 0.9-4.5 µM.

Crystal structure of (E)-N'-[1-(4-amino-phen-yl)ethyl-idene]-2-hy-droxy-5-iodo-benzohydrazide methanol monosolvate.

In the title compound, C15H14IN3O2·CH3OH, two aromatic rings are linked by an N-substituted hydrazide function. The dihedral angle between the aromatic rings is 10.53 (8)°. The stereochemistry about the imine function is E. The methanol mol-ecule forms an O-H⋯O hydrogen bond to the hydrazide O atom. In the crystal, chains of mol-ecules running along the c-axis direction are formed by O-H⋯O hydrogen bonds. Adjacent chains are linked through N-H⋯O hydrogen bonds and π-π stacking inter-actions. The inter-molecular inter-actions in the crystal packing were investigated using Hirshfeld surface analysis, which indicated that the most significant contacts are H⋯H (38.2%), followed by C⋯H/H⋯C (20.6%), O⋯H/H⋯O (11.1%) and I⋯H/H⋯I (9.7%).

Crystal structure and Hirshfield surface analysis of 4-phenyl-3-(thio-phen-3-ylmeth-yl)-1H-1,2,4-triazole-5(4H)-thione.

In the title compound, C13H11N3S2, the phenyl ring is twisted from the 1,2,4-triazole plane by 63.35 (9)° and by 47.35 (9)° from the thio-phene plane. In the crystal, chains of mol-ecules running along the c-axis direction are formed by N-H⋯S inter-actions [graph-set motif C(4)]. The 1,2,4-triazole and phenyl rings are involved in π-π stacking inter-actions [centroid-centroid distance = 3.4553 (10) Å]. The thio-phene ring is involved in C-H⋯S and C-H⋯π inter-actions. The inter-molecular inter-actions in the crystal packing were further analysed using Hirshfield surface analysis, which indicates that the most significant contacts are H⋯H (35.8%), followed by S⋯H/H⋯S (26.7%) and C⋯H/H⋯C (18.2%).

Green synthesis and crystal structure of 3-(benzo-thia-zol-2-yl)thio-phene.

The title compound, C11H7NS2, was prepared in high yield (87%) using a solvent-free microwave-assisted synthesis. The structure shows whole-mol-ecule disorder with occupancies for two orientations (A and B) of 0.4884 (10) and 0.5116 (10), respectively. The thio-phene and benzo-thia-zole rings are almost planar and make dihedral angles of 10.02 (18) and 12.54 (19)° for orientations A and B, respectively. Slipped π-π stacking between the aromatic rings, together with C-H⋯π, C-H⋯S and C-H⋯N inter-actions, result in a herringbone motif in the crystal packing.

Crystal structure of 4-amino-3-(thio-phen-3-ylmeth-yl)-1H-1,2,4-triazole-5(4H)-thione.

In the title compound, C7H8N4S2, the thio-phene ring shows rotational disorder over two orientations in a 0.6957 (15):0.3043 (15) ratio. The plane of the 1,2,4-triazole ring makes a dihedral angle of 75.02 (17)° with the major-disorder component of the thiophene ring. In the crystal, two types of inversion dimers, described by the graph-set motifs R22(8) and R22(10), are formed by N-H⋯S inter-actions. Chains of mol-ecules running in the [101] direction are linked by weaker N-H⋯N inter-actions. The thio-phene ring is involved in π-π and C-H⋯π inter-actions.

Crystal structure of N-(4-oxo-2-sulfanyl-idene-1,3-thia-zolidin-3-yl)-2-(thio-phen-3-yl)acetamide.

The title compound, C9H8N2O2S3, crystallizes with two mol-ecules (A and B) in the asymmetric unit. Both have similar conformations (overlay r.m.s. deviation = 0.209 Å) and are linked by an N-H⋯O hydrogen bond. In both mol-ecules, the thio-phene rings show orientational disorder, with occupancy factors of 0.6727 (17) and 0.3273 (17) for mol-ecule A, and 0.7916 (19) and 0.2084 (19) for mol-ecule B. The five-membered rings make an angle of 79.7 (2)° in mol-ecule A and an angle of 66.8 (2)° in mol-ecule B. In the crystal, chains of mol-ecules running along the a-axis direction are linked by N-H⋯O hydrogen bonds. The inter-action of adjacent chains through N-H⋯O hydrogen bonds leads to two types of ring structures containing four mol-ecules and described by the graph-set motifs R44(18) and R42(14).

Crystal structure of (2E)-1-(4-hy-droxy-1-methyl-2-oxo-1,2-di-hydro-quinolin-3-yl)-3-(4-hy-droxy-3-meth-oxy-phen-yl)prop-2-en-1-one.

In the title compound, C20H17NO5, the dihedral angle between the mean plane of the di-hydro-quinoline ring system (r.m.s. deviation = 0.003 Å) and the benzene ring is 1.83 (11)°. The almost planar conformation is a consequence of an intra-molecular O-H⋯O hydrogen bond and the E configuration about the central C=C bond. In the crystal structure, O-H⋯O hydrogen bonds generate chains of mol-ecules along the [10-1] direction. These chains are linked via π-π inter-actions [inter-centroid distances are in the range 3.6410 (16)-3.8663 (17) Å].