Precursor Structural Influences on the Final ZnO Nanoparticle Morphology from a Novel Family of Structurally Characterized Zinc Alkoxy Alkyl Precursors

We have synthesized a variety of structurally diverse "Zn(OR)(Et)(solv)" and "Zn(OR)2(solv)2" where Et = CH2CH3 and solv = no bound solvent, pyridine (py), tetrahydrofuran (THF), or 1-methyl imidazole (MeIm). The ligand OR represents the following: neo-pentoxide (ONep = OCH2CMe3), tert-butoxide (OBut = OCMe3), cycloalkane-substituted methoxide [(OCH2C(CH2)n, n = 2, OCH2Prc; n = 3, OCH2Buc], cyclopentoxide [OCH(CH2)4 = OPec], tetrahydrofurfurylalkoxide [OCH2CH(CH2)3O] = OTHF], and several aryloxides [OAr = 2,6-dimethyl phenoxide (DMP), 2,6-di-isopropyl phenoxide (DIP), and 2,6-di-tert-butyl phenoxide (DBP)]. These compounds were characterized by single-crystal X-ray diffraction as [Zn(OR)(Et)(py)]2 [OR = ONep (1), OBut (2)], [Zn(3-ONep)(Et)]4 (3), Zn[Zn3(3-OCH2Prc)4(Et)3]2 (4), [Zn(3-OCH2Buc) (Et)]4 (5), [Zn(3-OPec)(Et)]4 (6), Zn(OAr)(Et)(solv)2 where OAr = DMP: solv = py (7), DIP: solv = py (8), MeIm (8a); DBP: solv = py (9) and [Zn(DBP)(Et)]2 (9a), Zn(OAr)2(solv)2 where OAr = DMP: solv = py (10), MeIm (10a), py/MeIm (10b), DIP: solv = py (11), MeIm (11a), DBP: solv = py (12), MeIm A(12a), [Zn(3-OTHF)(Et)]4 (13). The solution state behavior of these compounds was explored by multinuclear NMR spectroscopy. In an effort to determine the effect of nuclearity on the final nanoparticle morphology and size, four representative nuclearities mono- (8), di- (1), tetra- (13), and hepta- (4) nuclear were chosen and used to generate nanoparticles of ZnO. The mononuclear compound formed polydispersed spherical nanoparticles of wurtzite, whereas the nanoparticles generated from the other samples were nanorods. A relationship between the precursors central core and the final morphological properties of the nanorods was proffered to explain the variations noted.