l-Cystine kidney stones—aggregates of single crystals of the hexagonal form of l-cystine—afflict more than 20 000 individuals in the United States alone. Current therapies are often ineffective and produce adverse side effects. Recognizing that the growth of l-cystine crystals is a critical step in stone pathogenesis, real-time in situ atomic force microscopy of growth on the (0001) face of l-cystine crystals and measurements of crystal growth anisotropy were performed in the presence of prospective inhibitors drawn from a 31-member library. The most effective molecular imposters for crystal growth inhibition were l-cystine mimics (aka molecular imposters), particularly l-cystine diesters and diamides, for which a kinetic analysis revealed a common inhibition mechanism consistent with Cabrera–Vermilyea step pinning. The amount of inhibitor incorporated by l-cystine crystals, estimated from kinetic data, suggests that imposter binding to the {0001} face is less probable than binding of l-cystine solute molecules, whereas imposter binding to {101̅0} faces is comparable to that of l-cystine molecules. These estimates were corroborated by computational binding energies. Collectively, these findings identify the key structural factors responsible for molecular recognition between molecular imposters and l-cystine crystal kink sites, and the inhibition of crystal growth. The observations are consistent with the reduction of l-cystine stone burden in mouse models by the more effective inhibitors, thereby articulating a strategy for stone prevention based on molecular design.

Guanidinium organodisulfonate (GDS) hydrogen-bonded frameworks constructed from "tetris-shaped" ortho-substituted disulfonated stilbene derivatives display crystal architectures in which the stilbenes serve as pillars that connect opposing guanidinium sulfonate (GS) sheets in a continuously layered architecture while guiding the organization of the stilbene residues into packing motifs that produce unique optical properties. The constraints imposed by orthosubstitution result in a heretofore unreported topology of the pillars projecting from the two-dimensional GS sheet, while the dense packing of stilbene constituents, confined between the GS sheets, results in strong intermolecular electronic coupling. Stilbene 420 (2,2″-([1,1′-biphenyl]-4,4′-diyldi-2,1-ethenediyl)bis-benzenesulfonate) pillars pack in a face-to-face brickwork motif, producing a large bathochromic shift (∼100 nm) of the absorbance and emission spectra relative to stilbene 420 in methanol. The distyrylbenzenedisufonate (2,2′-((1E,1′E)-1,4-phenylenebis(ethene-2,1-diyl))dibenzenesulfonate) pillars, which pack in a face-to-face herringbone motif between the GS sheets, afford both hypsochromic and bathochromic shifts in their absorption spectrum, indicative of an unusually large Davydov splitting. The observation of both bathochromic and hypsochromic shifts can be attributed to the herringbone arrangement, in which both transitions are allowed due to the nonzero vector sum of the transition dipoles in both states. The large magnitude of the Davydov splitting reflects the strong intermolecular coupling between the chromophores, enforced by confinement in the GS framework. The newly discovered GS architectures evoke a new design rule that permits prediction of GS topologies in the case of longer tetris-shaped pillars.

A simple and efficient synthesis of cyclopenta[l]phenanthrenes from substituted acetophenones provides access to polycyclic aromatics with a variety of substitution patterns. The synthesis requires only three steps from a silyl enol ether: a Mukaiyama aldol reaction followed by McMurry coupling and then Mallory photocyclooxidation to give the target phenanthrenes. Photocyclization conditions have been found that give regioselective formation of 2,7-phenanthrenes from bis(meta-substituted) stilbenes.

A commercially available combined X-ray diffraction – differential scanning calorimetry (XRD-DSC) stage was adapted for studies of gas loading in microporous materials, including metal organic frameworks (MOFs). Insertion of a custom-built humid atmosphere swing chamber (HASC) between a humidity generator and the XRD-DSC stage facilitates both humid atmosphere and vacuum swing gas loading. The HASC is necessary to buffer between the humidity generator and the XRD-DSC stage, allowing the gas mixture to homogenize prior to sample exposure, so that both humid atmosphere and vacuum swings could be performed. The changes in XRD can be used to follow structural changes, including collapse, which is indicative of a lack of microporosity upon activation, and the flexibity of frameworks upon gas sorption–desorption cycles. Measurements of the area under the DSC curve allows for calculation of the isosteric heat of adsorption (Qst; kJ molGAS−1). Vacuum-atmosphere swing experiments performed at different pressure steps allow for the reconstruction of the enthalpy of gas adsorption before and after a phase transition. These modes of operation are illustrated in three case studies from a program of exploratory MOF synthesis used to discover novel materials for selective gas sorption from humid gas streams: (1) gas binding in Stony Brook metal organic framework-1, (2) zeolitic imidazolate framework-7 response to variable pressure vacuum-atmosphere swing, and (3) high throughput evaluation of the selectivity of novel MOFs synthesized from customized linkers.

A new method to prepare phenanthro[9,10‐c]thiophenes has been developed. In the presence of triflic acid, 3,4‐diaryl thiophenes undergo 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ)‐promoted cyclo‐oxidation. NMR and computational studies indicate that protonation of the thiophene plays a key role in this reaction. The reaction can be used to prepare phenanthro[9,10‐c]thiophene, as well as derivatives with alkyl, bromo, and methoxy substituents. However, the yields and selectivity of the reaction depend on both the nature and location of the substituents. Bis(3‐methoxyphenyl)thiophene reacts under these conditions to give the desired product in 57 % yield, while bis(4‐methoxyphenyl)thiophene gives no product. Bis(3‐bromophenyl)thiophene did not react, but cyclo‐oxidation of bis(4‐bromophenyl)thiophene provides the desired product in 34 % yield.