A study of the pharmacological properties of pyrrolo[2,1-c][1,4]benzodiazepine derivatives led to the choice of (+)-1,2,3,11a-tetrahydro-10-methyl-5H-pyrrolol[2,1-c][1,4]benzodiazepine-5,11)10H)-dione as a candidate for anxiolytic evaluation in a limited clinical trial in man. Metabolism studies in laboratory animals have pointed to rapid hydroxylation, possibly in the 3 and 11a positions. A series of compouds containing methyl groups in one or more of these positions has been prepared in an effort to block metabolism and thereby obtain more active or longer acting compounds. All of these derivatives were less active than the parent compound.

Oxygen deficient cerium oxide cluster ions, Ce(n)O(m)(+) (n = 2-10, m = 1-2n) were prepared in the gas phase by laser ablation of a cerium oxide rod. The reactivity of the cluster ions was investigated using mass spectrometry, finding that oxygen deficient clusters are able to extract oxygen atoms from CO, CO2, NO, N2O, and O2 in the gas phase. The oxygen transfer reaction is explained in terms of the energy balance between the bond dissociation energy of an oxygen containing molecule and the oxygen affinity of the oxygen-deficient cerium oxide clusters, which is supported by DFT calculations. The reverse reaction, i.e., formation of the oxygen deficient cluster ions from the stoichiometric ones was also examined. It was found that intensive heating of the stoichiometric clusters results in formation of oxygen deficient clusters via Ce(n)O(2n)(+) → Ce(n)O(2n-2)(+) + O2, which was found to occur at different temperatures depending on cluster size, n.

The properties of small cerium oxide and gold−cerium oxide clusters were explored as analogues for gold deposition at defect sites on a cerium oxide surface. Ce 2 O n (n = 0−2) and AuCe 2 O n (n = 0− 2) clusters were prepared in the gas phase and investigated using photoionization efficiency spectroscopy complemented by spectral simulations based on DFT calculations; purely theoretical investigations were conducted on the Ce 2 O 3 , Ce 2 O 4 , AuCe 2 O 3 , and AuCe 2 O 4 clusters due to these species not being detected. The optimized AuCe 2 O n (n = 0−3) cluster geometries are consistent with Au adsorption to oxygen vacancy sites while the AuCe 2 O 4 cluster correlates with Au adsorption to a CeO 2 vacancy site. The electronic properties of the adsorbed Au atom depend strongly on the nature of the ceria adsorption site: O vacancyadsorbed Au is negatively charged with a Ce → Au charge transfer occurring at the adsorption interface, whereas Au adsorbed to a CeO 2 vacancy is positively charged with an Au → Ce charge transfer. The adsorbed Au atom is proposed to enhance the catalytic properties of the AuCe 2 O n cluster by (i) stabilizing the negatively charged Au atom on reduced AuCe 2 O n clusters to enhance nucleophilicity; (ii) increasing the electron accepting capability of the AuCe 2 O 4 species; (iii) destabilizing the HOMO of the AuCe 2 O 4 cluster; and (iv) facilitating the abstraction of additional surface oxygen atoms by reactants.

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