Synthesis of zirconium guanidinate complexes and the formation of zirconium carbonitride via low pressure CVD

Thin films of zirconium carbonitride have been deposited on glass at 600 °C from two novel guanidinate precursors: [ZrCp'{¿2-(iPrN)2CNMe2}2Cl] (1) and [ZrCp'2{¿2-(iPrN)2CNMe2}Cl] (2) (Cp' ) monomethylcyclopentadienyl). Both compounds 1 and 2 were structurally characterized by X-ray crystallography. The films grown via low pressure chemical vapor deposition (LPCVD) from compound 1 were mirrorlike with a red-brown sheen whereas those from 2 were gray. Chlorine was present in the films although the levels were no higher than 3 at.%. These two compounds clearly show how the coordination environment around the metal center affects the composition of the film, as films from 1 were nitrogen rich and those from 2 were carbon rich. The films were uniform, adhesive, abrasion resistant, conformal, and hard, being resistant to scratching with steel and brass scalpels

Photoinduced hole transfer in QD–phthalocyanine hybrids

A series of CdSe quantum dot (QD)–phthalocyanine (Pc) hybrids were synthesized and their photophysics was studied using steady state and time-resolved spectroscopic methods. Emission of QDs was progressively quenched upon increasing the concentration of Pc in the hybrids. A detailed transient absorption study of the hybrids revealed that the mechanism of quenching is charge separation, resulting in the formation of hybrids with negatively charged QDs and the Pc cation. Direct photo-excitation of Pc did not show any detectable interaction between the excited state of Pc and the QD to which it is attached. An explanation is proposed, based on the suggestion that the energy of the lowest unoccupied molecular orbital (LUMO) of Pc is lower than the lower edge of the QD conduction band, while the energy of the highest occupied molecular orbital (HOMO) of Pc is sufficiently higher than the high energy edge of the QD valence band (VB), thus permitting hole transfer from the QD VB to the Pc HOMO after photo-excitation of QDs.acceptedVersionPeer reviewe

Bis(cyclopentadienyl) zirconium(IV) amides as possible precursors for low pressure CVD and plasma-enhanced ALD

Low pressure chemical vapour deposition (LPCVD) of [ZrCp2(NMe2)2] (1), [ZrCp2(¿2-MeNCH2CH2NMe)] (2), [ZrCp'2(NMe2)2] (3) and [ZrCp'2(NEt2)2] (4) (Cp = ¿5-cyclopentadienyl, Cp' = ¿5-monomethylcyclopentadienyl), onto glass substrates at 600 °C, afforded highly reflective and adhesive films of zirconium carbide and amorphous carbon. Powder XRD indicated that the films were largely amorphous, although small, broad peaks accounting for ZrC and ZrO2 were present, suggesting that the remaining carbon was due to amorphous deposits from the cyclopentadienyl ligands. SEM images showed an island-growth mechanism with distinct crevices between the concentric nodules. Plasma-enhanced atomic layer deposition (PEALD) of compounds 1 and 2 showed that the precursors were not sufficiently stable or volatile to give a good rate of film growth