Donor-σ-Acceptor (D-σ-A) molecules, arrayed in a monolayer between electrodes, can serve as molecular rectifiers. Using perylene-3,4,9,10-tetracarboxylic bisimide (PBI) as the acceptor allows the attachment of the donor group to one imide nitrogen and a solubilizing swallowtail, normally a long (e.g., C19) alkane connected at midchain, on the other. Such an alkyl tail facilitates the formation of Langmuir–Blodgett (LB) monolayers. We have employed several modified swallowtails to make new D-σ-A molecules: poly(ethylene glycol) (PEG) swallowtails with 6 ether oxygens or with 4 ether oxygens to promote hydrophilicity in orienting LB monolayers, and alkyl swallowtails ending with sulfur anchors (thioacetate, thiol, or methyl disulfide) to stabilize attachment of the D-σ-A molecules to gold electrodes. The preparation and characterization of D-σ-A molecules containing combinations of these swallowtails with pyrene, ferrocene, and tetramethylphenylenediamine donor groups is described.

AxVF3 (A=KA=K, Rb, Cs; x=0–1.0x=0–1.0) and AxCrF3 compounds were sealed inside high-temperature DTA molybdenum sample cups using electron beam welding techniques. Melting temperatures of the AxVF3 compounds ranged from 1050 to 1400 °C; those of AxCrF3 from 850 to 1200 °C. Reconstructive transitions were observed for AxVF3 compounds between 650 and 950 °C, and for AxCrF3 compounds between 550 and 825 °C. A displacive transition was observed to occur in VF3 at 490 °C. Order–disorder transitions were determined by X-ray diffraction techniques. In the AxVF3 compounds, electronic ordering and ordering of partially filled A+ sites were observed to occur between 100 and 300 °C. Ordering phenomena in the AxCrF3 compounds (in addition to electronic ordering and ordering of partially filled A+ sites) included Jahn–Teller cooperative ordering. These compounded transitions occurred between 300 and 500 °C.Melting temperature versus x of KxVF3 and KxCrF3.