No abstract

The mol­ecule of the title chalcone derivative, C18H17BrO4, is twisted, the dihedral angle between the 4-bromo­phenyl and 2,4,6-trimethoxy­phenyl rings being 39.17 (6)°. The three meth­oxy groups are oriented in two different conformations whereby two meth­oxy groups are coplanar, whereas the third is twisted with respect to the attached benzene ring [C—O—C—C torsion angles of −2.84 (18), −2.80 (18) and −9.31 (18)°]. Weak intra­molecular C—H⋯O inter­actions generate two S(5) and one S(6) ring motifs. In the crystal structure, mol­ecules are linked into supra­molecular sheets parallel to the bc plane by weak C—H⋯O inter­actions. These sheets are stacked along the a axis. The crystal structure is further stabilized by weak C—H⋯π inter­actions.

The mol­ecule of the title heteroaryl chalcone, C16H16O4S, which consists of substituted thio­phene and benzene rings bridged by the prop-2-en-1-one group, is slightly twisted. The dihedral angle between the thio­phene and 3,4,5-trimethoxy­phenyl rings is 12.18 (4)°. The three meth­oxy groups have two different conformations; two meth­oxy groups are coplanar [C—O—C—C torsion angles = −1.38 (12) and 0.47 (12)°] whereas the third is (-)-synclinal with the benzene ring. In the crystal structure, adjacent mol­ecules are linked in a face-to-side manner into chains along the c axis by weak C—H⋯O(enone) inter­actions. These chains are stacked along the b axis by weak C—H⋯O(meth­oxy) inter­actions.

Three series of heteroaryl chalcones, (E)-1-(2-pyridyl)-3-(X)prop-2-en-1-one (Ia-Ic), (E)-1-(2-thienyl)-3-(X)prop-2-en-1-one (IIa-IIc), and (E)-1-(2-furyl)-3-(X)prop-2-en-1-one (IIIa-IIIc), where X = 2,4,5-trimethoxyphenyl (for series a), X = 2,4,6-trimethoxyphenyl (for series b), and X = 3,4,5-trimethoxyphenyl (for series c) were synthesised using basic catalysed aldol condensation and characterised using 1H NMR and FT-IR spectroscopies. Compound IIa was also characterised by single crystal X-ray analysis. The absorption and fluorescence emission spectra of these compounds revealed that the absorption and fluorescence depended on the heterocycle rings and trimethoxysubstituted phenyl rings linked to the enone system. The position of methoxy groups substantially affected the fluorescent properties. Compounds Ia-IIIa containing the 2,4,5-trimethoxyphenyl moiety exhibited the red-shift phenomenon and strong emission fluorescence.

There are two crystallographically independent mol­ecules in the asymmetric unit of the title heteroaryl chalcone, C21H14OS: the dihedral angle between the thio­phene and anthracene rings is 75.07 (17)° in one mol­ecule and 76.32 (17)° in the other. The crystal structure is consolidated by short C⋯O [3.348 (5)–3.394 (5) Å], C⋯S [3.607 (5)–3.666 (5) Å] and S⋯O [2.926 (3) Å] contacts, as well as by C—H⋯π and π–π inter­actions [Cg⋯Cg = 3.745 (3) Å].