Insights into the compositional and temperature-mediated magnetic characteristics of chromium-doped ZnO nanoparticles.

This study explores the influence of chromium content and temperature on the magnetic characteristics of ZnO synthesized via the cost-effective coprecipitation approach. The host ZnO structure is not significantly changed by chromium doping, even at 5 wt.% of chromium concentration, according to x-ray diffraction studies. The Zn-O characteristic stretching vibration band at 480 cm-1and the other functional group attached to the Cr-doped ZnO nanoparticles are confirmed by Fourier-transform infrared (FTIR) spectroscopy studies. Diffuse reflectance spectroscopy analysis shows the interaction between chromium ions and ZnO causes bandgap narrowing, and the observed optical bandgap values fall as chromium content increases in the host ZnO matrix. Point defects such as zinc interstitial, zinc vacancy, and oxygen vacancy that exist in the Cr-doped ZnO nanoparticles are inveterate through photoluminescence spectroscopy. Vibrating sample magnetometry investigations reveal weak ferromagnetic behavior at low applied fields and diamagnetic signatures dominating at high applied fields in the Cr-doped ZnO nanoparticles at 300 K. The magnetic characteristics are also tunable in terms of temperatures, which opens new avenues for fabricating dilute magnetic semiconductors with various applications.

9-(2,4-Di-fluoro-phen-yl)-3,3,6,6-tetra-methyl-3,4,5,6,7,9-hexa-hydro-2H-xanthene-1,8-dione.

In the title compound, C23H24F2O3, the central pyran ring has a flat-boat conformation, whereas the two fused cyclo-hexenone rings adopt envelope conformations, with the C atom bearing the dimethyl substituent being the flap atom in each case. The pyran ring mean plane and the di-fluoro-phenyl ring are almost normal to each other, making a dihedral angle of 87.55 (4)°. In the crystal, mol-ecules are linked by pairs of C-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(8) ring motif. The F atom at position 2 on the di-fluoro-phenyl ring is disordered over the 2- and 6-positions, and has a refined occupancy ratio of 0.932 (3):0.068 (3).

2-(4-Fluoro-phen-yl)-1-(3-meth-oxy-phen-yl)-4,5-dimethyl-1H-imidazole.

In the title compound, C18H17FN2O, the imidazole ring makes dihedral angles of 68.81 (6) and 25.20 (8)° with the meth-oxy-phenyl and fluoro-phenyl rings, respectively. The dihedral angle between the meth-oxy-phenyl and fluoro-phenyl ring is 71.89 (6)°. In the crystal, mol-ecules are linked into inversion dimers with an R 2 (2)(8) graph-set motif by pairs of weak C-H⋯F inter-actions.

2,4-Bis(4-fluoro-phen-yl)-1,5-dimethyl-3-aza-bicyclo-[3.3.1]nonan-9-one.

The asymmetric unit of the title compound, C22H23F2NO, contains two independent mol-ecules, A and B. The bicyclic system adopts a twin-chair conformation in both mol-ecules. The dihedral angles between the fluoro-phenyl rings are 55.27 (8) and 56.37 (7)° in mol-ecules A and B, respectively. The NH groups are not involved in hydrogen bonding due to the steric hindrance of fluoro-phenyl groups. The crystal structure features weak C-H⋯O inter-actions.

1-(3-Meth-oxy-phen-yl)-4,5-dimethyl-2-phenyl-1H-imidazole.

In the title compound, C18H18N2O, the imidazole ring makes dihedral angles of 68.26 (7) and 22.45 (9)° with the meth-oxy-phenyl and phenyl rings, respectively. The dihedral angle between the meth-oxy-phenyl and phenyl ring is 71.86 (7)°. In the crystal, weak inter-molecular C-H⋯O and C-H⋯N hydrogen bonds link the mol-ecules into columns propagated in [101].

2,4-Bis(furan-2-yl)-1,5-dimethyl-3-aza-bicyclo-[3.3.1]nonan-9-one.

In the title compound, C18H21NO3, the bicyclic ring system adopts a twin-chair conformation. The two methyl groups attached to the bicycle are in an equatorial orientation for both rings. One of the furan rings is disordered over two orientations with an occupancy ratio of 0.686 (6):0.314 (6). In the crystal, very long N-H⋯O hydrogen bonds connect the mol-ecules into a chain perpendicular to the ac plane.

Propan-2-yl r-4-(4-fluoro-phen-yl)-3-hy-droxy-c-6-methyl-2-phenyl-4,5-dihydro-2H-indazole-t-5-carboxyl-ate.

In the title compound, C(24)H(23)FN(2)O(3), the cyclo-hexene ring adopts a screw-boat conformation. The fluorobenzene ring attached to the cyclo-hexene ring and the phenyl ring attached to the indazole moiety are inclined to one another by 57.77 (13)°. In the crystal, mol-ecules are linked by O-H⋯N and C-H⋯O hydrogen bonds, forming chains with C(5) and C(10) graph-set motifs. There are also C-H⋯π inter-actions present. The isopropoxycarbonyl group undergoes considerable thermal motion.

16α,17α-Ep-oxy-17ß-(1H-imidazol-1-yl)androst-4-en-3-one monohydrate.

In the title compound, C(22)H(28)N(2)O(2)·H(2)O, rings B and C adopt chair conformations. Ring A adopts an envelope conformation, with the non-fused C atom adjacent to the fused C atom bearing a methyl group as the flap atom. Ring D also adopts an envelope conformation, with the fused C atom not bearing a methyl group as the flap atom. The water mol-ecule links the mol-ecules via O-H⋯O and O-H⋯N hydrogen bonds, forming zigzag chains which run parallel to the c axis. Weak C-H⋯O inter-actions also occur.

c-5-Hy-droxy-r-2,c-4-bis-(meth-oxy-carbon-yl)-t-5-methyl-t-3-(3-nitro-phen-yl)cyclo-hexa-none.

In the title compound, C(17)H(19)NO(8) [systematic name = dimethyl 4-hydroxy-4-methyl-2-(3-nitrophenyl)-6-oxocyclohexane-1,3-dicarboxylate], the cyclo-hexa-none ring exhibits a chair conformation. The meth-oxy-carbonyl groups are oriented in opposite directions with respect to the cyclo-hexa-none ring. In the crystal, O-H⋯O hydrogen bonds links the mol-ecules into chains running parallel to the a axis. These chains are connected by weak C-H⋯O hydrogen bonds, forming sheets parallel to the ab plane.