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Porphyrins and metalloporphyrins have unique chemical and electronic properties and thus provide useful model structures for studies of nanoscale electronic properties. The rigid planar structures and π-conjugated backbones of porphyrins convey robust electrical characteristics. For our investigations, cobaltacarborane porphyrins were synthesized using a ring-opening zwitterionic reaction to produce isomers with selected arrangements of carborane clusters on each macrocycle. Experiments were designed to investigate how the molecular structure influences the selforganization, surface assembly, and conductive properties of three molecular structures with 2, 4, or 8 cobaltacarborane substituents. Current versus voltage (I-V) spectra for designed cobaltacarborane porphyrins deposited on conductive gold substrates were acquired using conductive probe atomic force microscopy (CP-AFM). Characterizations with CP-AFM provide capabilities for obtaining physical measurements and structural information with unprecedented sensitivity. We found that the morphology of cobaltacarborane porphyrin structures formed on surfaces depends on a complex interplay of factors such as the solvent used for dissolution, the nature of the substrate, and the design of the parent molecule. The conductive properties of cobaltacarborane porphyrins were observed to change according to the arrangement of cobaltacarborane substituents. Specifically, the number and placement of the cobaltacarborane ligands on the porphyrin macrocycle affect the interactions that drive porphyrin self-assembly and crystallization. Interestingly, coulombic staircase I-V profiles were detected for a porphyrin with two cobaltacarborane substituents. [ABSTRACT FROM AUTHOR]

A series of seven BODIPYs functionalized with ortho-carborane groups at the 8(meso) or 3/5(α) position were synthesized and characterized by NMR, HRMS, HPLC, and in the cases of 2b and 5b, by X-ray analysis. The BODIPYs exhibited low dark toxicity and phototoxicity toward human glioma T98G cells, and their cellular uptake varied significantly, with 5b accumulating the most and 7 the least. All BODIPYs localized mainly within the cell ER. The BODIPYs showed higher permeabilities than lucifer yellow across human hCMEC/D3 brain endothelial cell monolayers as the BBB model. Among this series, 1b showed the highest BBB permeability (Pe = 16.4 × 10-5 cm/s), probably as a result of its lower MW (366 Da) and favorable hydrophobicity (log P = 1.5). The combination of low cytotoxicity, amphiphilicity, high boron content, high cellular uptake, and moderate BBB permeability renders these compounds promising boron delivery agents for the BNCT of brain tumors. [ABSTRACT FROM AUTHOR]

A series of four BODIPYs containing one or two ortho - or para -carborane clusters were synthesized using palladium(0)-catalyzed Suzuki cross-coupling or nucleophilic substitution reactions, at the 2,6- or the 8-positions of halogenated boron dipyrromethenes (BODIPYs). The spectroscopic, structural (including one X-ray) and in vitro BBB permeability of the BODIPYs using hCMEC/D3 brain endothelial cells were investigated. [ABSTRACT FROM AUTHOR]