Pumsak Ruanwas

4-Bromo-N-(4-meth­oxy-2-nitro­phen­yl)benzamide

In the title compound, C14H11BrN2O4, the amide segment makes dihedral angles of 23.4 (2) and 20.5 (2)° with the benzene rings, while the dihedral angle between the bezene rings is 2.90 (8)°. The nitro and methoxy groups are almost coplanar with their bound benzene ring, with the r.m.s. deviation for the 11 non-H atoms being 0.0265 (1) Å. An intramolecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, molecules are linked into [2-10] chains by weak C—H⋯O and C—H⋯Br interactions, which form an R 2 2(8) motif between pairs of molecules in the chain. A Br⋯O [3.2018 (12) Å] short contact also occurs.

(E)-1-(4-Aminophenyl)-3-(2,4,5-trimethoxyphenyl)prop-2-en-1-one

Molecules of the title aminochalcone, C18H19NO4, are twisted, with a dihedral angle of 11.26 (6)° between the 4-aminophenyl and 2,4,5-trimethoxyphenyl rings. The conformations of the three methoxy groups with respect to the benzene ring are slightly different. Two methoxy groups are almost coplanar with the attached benzene ring [C—O—C—C torsion angles of −1.45 (19) and 1.5 (2)°], while the third is (−)-synclinal with the attached benzene ring [C—O—C—C = −81.36 (17)°]. In the crystal structure, molecules are stacked into columns along the b axis and molecules in adjacent columns are linked by N—H⋯O hydrogen bonds into V-shaped double columns. Weak π–π interactions are also observed, with a centroid-centroid distance of 3.7532 (8) Å.

Synthesis, antityrosinase activity of curcumin analogues, and crystal structure of (1E,4E)-1,5-bis(4-ethoxyphenyl)penta-1,4-dien-3-one

Five derivatives of curcumin analogue (R = OCH2CH3 (1), R = N(CH3)2 (2), R = 2,4,5-OCH3 (3), R = 2,4,6-OCH3 (4), and R = 3,4,5-OCH3 (5)) were synthesized and characterized by 1H NMR, FT-IR and UV–Vis spectroscopy. The synthesized derivatives were screened for antityrosinase activity, and found that 4 and 5 possess such activity. The crystal structure of 1 was determined by single crystal X-ray diffraction: monoclinic, sp. gr. P21/c, a = 17.5728(15) Å, b = 5.9121(5) Å, c = 19.8269(13) Å, β = 121.155(5)°, Z = 4. The molecule 1 is twisted with the dihedral angle between two phenyl rings being 15.68(10)°. In the crystal packing, the molecules 1 are linked into chains by C−H···π interactions and further stacked by π···π interactions with the centroid–centroid distance of 3.9311(13) Å.

FLUORESCENCE PROPERTIES OF DIENONE DERIVATIVES AND SOLVENT EFFECTS ON THEIR FLUORESCENCE ABSORPTION AND EMISSION

Five dienone derivatives, (1E,4E)-1,5-bis(4-R-phenyl)penta-1,4-dien-3-one (1–5), R = OH (1), OCH3 (2), OCH2CH3 (3), N(CH3)2 (4) and N(CH2CH3)2 (5) have been synthesized and characterized by 1H- and 13C-NMR, UV-Vis and FT-IR spectroscopy and investigated for their fluorescence properties. The compounds under test possess fluorescence properties. The fluorescence absorption and emission maxima of 1–5 were found in the range 421–431 nm and 514–555 nm, respectively, leading to Stokes shifts ranging from 4099 to 5735 cm−1. Further, the effects of solvents on λabs (absorption) and λem (emission) of 4 and 5 were determined and noticed that the absorption spectra of these compounds were not significantly altered. While, the emission peak of 4 was shifted in CHCl3 (red shift) and 5 was shifted in EtOH (red shift) and hexane (blue shift). Analysis revealed that the compounds 4 and 5 are promising fluorescent probes with good fluorescence properties.

Synthesis, Characterization, Antioxidant, and Antibacterial Activities of 2-Aminochalcones and Crystal Structure of (2E)-1-(2-aminophenyl)-3-(4-ethoxyphenyl)-2-propen-1-one

Five 2-aminochalcone derivatives [R = H(1), R = OCH2CH3(2), R = 2,4,5-OCH3(3), R = 3,4,5-OCH3(4), and R = thiophene(5)] were synthesized and characterized by 1H NMR, FT-IR, and UV-Vis spectroscopy. Crystal structure of 2 was also determined by single crystal X-ray diffraction. Compound 2 crystallizes in a monoclinic P21/n space group with the unit cell parameters a = 32.804(7) Å, b = 4.9972(11) Å, c = 21.7173(3) Å, β = 128.440(4)°, V = 2788.4(10) Å3, and Z = 8. There are two molecules in an asymmetric unit of 2, the molecular structure of 2 is twisted with the dihedral angle between the two phenyl rings being 13.6(3)° in one molecule and 7.1(3)° in the other. In the crystal packing, the molecules of 2 are linked into chains along the b-axis by C‒H⋅⋅⋅O interactions. Antioxidant and antibacterial activities of 1–5 were also carried out.

Five different colours solid-state fluorescence of azastilbenes: a new push–pull π-conjugated system

Five push–pull azastilbene derivatives [R = −OH (1), −OCH3(2), −OCH2CH3(3), −N(CH3)2 (4) and −N(CH2CH3)2(5)] have been synthesized and successfully characterized by 1H NMR, ultraviolet–visible (UV–Vis) and Fourier-transform infrared (FT-IR) spectroscopy. Compounds 1–5 possess solid-state fluorescence in five different colours ranging from blue to orange (λex at 400 nm) in which blue (λem at 474 nm) for 1, bright-blue (λem at 469 nm) for 2, green (λem at 537 nm) for 3, yellow (λem at 568 nm) for 4 and orange (λem at 540, 630 nm) for 5. Compounds 4 and 5 exhibited strong fluorescence with quantum yield values 0.61 and 0.84, respectively, higher than those of 1–3. Moreover, liquid-state fluorescence performed in non-polar solvent in order to investigate the effect of dipolar intermolecular interactions on their fluorescence properties, the results revealed that the emission spectra of 1 −5 in liquid state are similar to those of solid state, indicating that no significant dipolar interactions were observed. Therefore, the substituent with electron-donating group as N- or O-donor and electron-withdrawing group as –SO3H, on the azastilbene skeleton play a major role on their solid-state fluorescence.

(E)-4-[4-(Diethyl­amino)­benzyl­idene­ammonio]­benzene­sulfonate

The title compound, C17H20N2O3S, synthesised from sulfanilic acid and 4-diethylaminobenzaldehyde, crystallized out as a zwitterion with the central N atom protonated. The zwitterion exists in an E conformation with respect to the C=N double bond. The dihedral angle between the benzene rings is 37.57 (5)°. In the crystal, the zwitterions are linked into a tape along the a axis by N—H⋯O hydrogen bonds. The crystal structure is further stabilized by weak C—H⋯O interactions and π–π interactions with a centroid–centroid distance of 3.8541 (6) Å. An O⋯O [2.8498 (11) Å] short contact is present.

4-Bromo-N-phenyl­benzamide

The molecule of the title benzamide derivative, C13H10BrNO, is twisted with the dihedral angle between the phenyl and 4-bromophenyl rings being 58.63 (9)°. The central N—C=O plane makes dihedral angles of 30.2 (2) and 29.2 (2)° with the phenyl and 4-bromophenyl rings, respectively. In the crystal, molecules are linked by N—H⋯O hydrogen bonds into chains along [100]. C—H⋯π contacts combine with the N—H⋯O hydrogen bonds, to form a three-dimensional network.

(E)-2-[4-(Dimethyl-amino)styr-yl]-1-methyl-quinolinium 4-methyl-benzene-sulfonate monohydrate.

In the title compound, C20H21N2 +·C7H7O3S−·H2O, the cation is essentially planar, as indicated by the dihedral angle of 2.79 (13)° between the quinolinium and the dimethylaminophenyl rings, and exists in the E configuration. The π-conjugated planes of the cation and the anion are inclined to each other at a dihedral angle of 66.95 (12)°. The cation is linked to the anion through C—H⋯O hydrogen bonds and the anion is further linked with the water molecule by O—H⋯O hydrogen bonds, forming a three-molecule unit. These units are arranged in a face-to-face manner into a ribbon-like structure along the b axis. The ribbons are stacked along the c axis. The crystal structure is further stabilized by C—H⋯π interactions involving the dimethylaminophenyl and methylphenyl rings. A π–π interaction with a centroid–centroid distance of 3.6074 (19) Å is also observed.

2-[(E)-2-(4-Ethoxy-phen-yl)ethen-yl]-1-methyl-pyridinium iodide monohydrate.

In the title compound, C16H18NO+·I−·H2O, the cation is essentially planar, with a dihedral angle of 3.13 (16)° between the pyridinium and benzene rings. The molecule adopts an E configuration with respect to the alkene double bond. In the crystal structure, the cations are packed in an anti-parallel manner through π–π interactions between adjacent pyridinium and benzene rings along the a axis, with centroid-to-centroid distances of 3.615 (2) and 3.630 (2) Å. Water molecules bind the iodide ions through O—H⋯I hydrogen bonds into layers. These layers link with the cations through weak C—H⋯O and C—H⋯I interactions.