Auto-fluorescent mesoporous ZnO nanospheres for drug delivery carrier application.

The zinc oxide (ZnO) nanostructures are very interesting materials because of their practical bio-applications in various areas such as drug delivery, construction of biomaterial, optical and acoustic devices as well as their bactericidal properties. Herein, we have prepared spheroidal mesoporous auto-fluorescent ZnO nanospheres by modified continuous distillation method, showed a blue emission in the concentration of 2mg/ml at 444nm. The auto-fluorescent property of ZnO nanospheres can be used in biomaterials for target sites of tissues/cells, thereby enabling site drug delivery especially in cancer therapy. Initially, the auto-fluorescent property of the ZnO material was characterized by different techniques like PXRD, FESEM with EDAX graph, TEM, ICP-OES, particle sizes, zeta potentials and BET analysis. The mesoporous ZnO nanospheres has attracted well for their crystalline, functionalized and intensified fluorescent properties. The surface of the ZnO nanospheres was porous, spherical and nanometric in size. The synthesized material has enormous potential as a nano-drug-carrier. Preliminary studies indicated that the material prepared has an excellent scope for detection and delivery at the site of therapeutic action.

Methyl 2-(5-chloro-1-methyl-2-oxo-2,3-di-hydro-1H-indol-3-ylidene)acetate.

The title compound, C12H10ClNO3, the indoline ring system is essentially planar, with a maximum deviation of 0.009 Šfor the N atom. The indoline ring and acetate group are essentially coplanar, with a maximum deviation of 0.086 Šfor the O atom. The mean plane through the methoxy-carbonyl-methyl group forms a dihedral angle of 3.68 (5)° with the plane of the indoline ring system. The mol-ecular structure is stabilized by an intra-molecular C-H⋯O hydrogen-bond inter-action. In the crystal, π-π stacking inter-actions [centroid-centroid distance = 3.7677 (8) Å] occur between benzene rings, forming a chain running along the c-axis direction.

rac-Methyl (1R,3'S)-1',1''-dimethyl-2,2''-dioxo-2H-dispiro-[acenaphthyl-ene-1,2'-pyrrolidine-3',3''-indoline]-4'-carboxyl-ate.

In the title compound, C(26)H(22)N(2)O(4), the pyrrolidine ring adopts a twisted conformation and the other five-membered rings adopt envelope conformations with the spiro C atoms as the flap atoms. The naphthalene ring system of the dihydro-acenaphthyl-ene group forms dihedral angles of 89.2 (9) and 75.5 (6)° with the pyrrolidine and indole rings, respectively. The pyrrolidine ring makes a dihedral angle of 80.1 (9)° with the indole ring. In the crystal, mol-ecules are linked by weak C-H⋯O hydrogen bonds, forming chains along the b-axis direction.

2-Chloro-8,8-dimethyl-8,9-dihydro-7H-chromeno[2,3-b]quinoline-10,12-dione.

The asymmetric unit of the title compound, C(18)H(14)ClNO(3), contains two independent mol-ecules (A and B). In both mol-ecules, the cyclo-hexa-none ring has a chair conformation. The dihedral angles between the pyran ring and the pyridine and chloro-phenyl rings are 2.13 (9) and 2.19 (9)°, respectively, in A, and 0.82 (9) and 1.93 (9)°, respectively, in B. The carbonyl O atoms deviate from the pyran and benzene rings to which they are attached by -0.092 (2) and 0.064 (2) Å, respectively, in A, and by -0.080 (2) and -0.063 (2) Å, respectively, in B. In the crystal, the A mol-ecules are linked via C-H⋯O hydrogen bonds, forming double-stranded chains along [100]. They lie parallel to the double-stranded chains formed by the B mol-ecules, which are also linked via C-H⋯O hydrogen bonds. The chains stack up the c axis in an -A-A-B-B-A-A- manner, with a number of π-π inter-actions involving A and B mol-ecules; the centroid-centroid distances vary from 3.4862 (11) to 3.6848 (11) Å

8,8-Dimethyl-8,9-dihydro-7H-chromeno[2,3-b]quinoline-10,12-dione.

In the title compound, C(18)H(15)NO(3), the fused benzopyran and pyridine rings are essentially coplanar [r.m.s. deviation = 0.0533 Šwith a maximum deviation of 0.080 (1) Šfor a benzene C atom]. The cyclo-hexa-none ring adopts an envelope conformation with the dimethyl-substituted C atom 0.660 (2) Šout of the plane formed by the remaining ring atoms (r.m.s. deviation = 0.0305 Å). The dihedral angle between the mean planes of the pyran and cyclo-hexa-none rings is 12.95 (6)°. In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds, leading to chains running along [011].

Methyl (3R*,3'S*)-1',1''-dimethyl-2,2''-dioxodispiro-[indoline-3,2'-pyrrolidine-3',3''-indoline]-4'-carboxyl-ate.

In the title compound, C(22)H(21)N(3)O(4), the central pyrrolidine ring adopts an envelope conformation with the N atom in the flap position. The indoline ring systems are almost perpendic-ular to the mean plane of the pyrrolidine ring, making dihedral angles of 86.4 (8) and 83.1 (8)°. The acetate group attached to the pyrrolidine ring assumes an extended conformation. In thecrystal, N-H⋯O hydrogen bonds result in the formation of a C(7) chain running along [100]. The crystal packing also features π-π inter-actions [centroid-centroid distance = 3.2032 (11) Å].

Methyl (3S,3'R)-1-methyl-2,2''-dioxo-1',2',3',5',6',7',8',8a'-octa-hydro-dispiro-[indoline-3,2'-indolizine-3',3''-indoline]-1'-carboxyl-ate.

In the title compound, C(25)H(25)N(3)O(4), the central pyrrolidine ring and the two pyrrolidine rings adopt twisted conformations, whereas the piperidine ring in the octa-hydro-indolizine fused ring system adopts a chair conformation. The indoline ring systems are almost perpendicular with respect to the mean plane of the octa-hydro-indolizine ring system, making dihedral angles of 84.4 (5) and 79.4 (5)°. The acetate group attached to the octa-hydro-indolizine ring system assumes an extended conformation. In the crystal, N-H⋯O hydrogen bonds result in the formation of a helical C(7) chain running parallel to [101]. The crystal packing features C-H⋯O hydrogen bonds and C-H⋯π inter-actions.

3'-[Hy-droxy(4-oxo-4H-chromen-3-yl)meth-yl]-2-oxospiro-[indoline-3,2'-pyrrolidine]-3'-carbonitrile.

In the title compound, C(23)H(19)N(3)O(4), the pyran ring adopts a half-chair conformation, while the pyrrolidine (with a C atom as the flap atom) and the five-membered ring in the indoline (with a C atom as the flap atom) ring system adopt slight envelope conformations. The pyrrolidine ring makes dihedral angles of 83.3 (1) and 60.4 (1)° with the mean plane through all non-H atoms of the indoline and chromene ring systems, respectively. In the crystal, mol-ecules are connected by two unique N-H⋯O and O-H⋯O hydrogen-bonding inter-actions, which form centrosymmetric patterns described by graph-set motifs R(2) (2)(18) and R(2) (2)(14). These two motifs combine to form a hydrogen-bonded chain which propagates in the a-axis direction. The crystal structure is also stablized by C-H⋯O inter-actions and by aromatic π-π stacking inter-actions between the pyran and benzene rings of neighbouring mol-ecules [centroid-centroid distance = 3.755 (1) Šand slippage = 1.371 (2) Å].

A triclinic polymorph of methyl (3R,3'S)-1',1''-dimethyl-2,2''-dioxodispiro-[indoline-3,2'-pyrrolidine-3',3''-indoline]-4'-carboxyl-ate.

In the title compound, C22H21N3O4, the central pyrrolidine ring adopts a C-envelope conformation with a C atom 0.6593 (13) Šdisplaced from the mean plane formed by the remaining ring atoms. The indoline ring systems (r.m.s. devisations of 0.0356 and 0.0547 Å) are almost perpendicular to the mean plane of the pyrrolidine ring, making dihedral angles of 89.7 (6) and 82.5 (6)°. The acetate group attached to the pyrrolidine ring assumes an extended conformation. In the crystal,N-H⋯O and C-H⋯O hydrogen bonds connect adjacent molecules, forming an infinite tape extending along [1-1-1]. The crystal packing is further consolidated by strong π-π inter-actions with a centroid-centroid distance of 3.2585 (8) Å. The title compound is a polymorph of previously reported monoclinic structure [Ganesh et al. (2012 ▶). Acta Cryst. E68, o2902-o2903].