The Role of Conglomerate Crystallization in Spontaneous Resolution and Chiral Amplification

The mystery of the origin of homochirality in Nature has been thoroughly investigated due to the essential role it plays in Chemistry, Biochemistry and Biology. For example, enantiopure compounds are often essential in the pharmaceutical and agrochemical industries. New aspects of chemistry and chirality can be explored by effectively utilizing the unique nature of conglomerate crystals. In some cases, conglomerate crystals can be easily resolved by carefully observing the features of the crystals. Resolution is possible through observation of hemihedrism, macromorphology, circular polarization or various surface features. Cytosine and 1,2-bis(N-benzoyl-N-methylamino)benzene are two examples of compounds that form centrosymmetric monohydrate racemic crystals but non-centrosymmetric anhydrous conglomerate crystals. Herein, a novel approach to asymmetric amplification by coupling conglomerate crystal formation via dehydration, with subsequent Viedma ripening (i.e. attrition-enchanced deracemization) is being explored. A systematic search of the Cambridge Crystallographic Database for other crystal systems which can undergo desolvation and subsequent chiral amplification is ongoing. Enantiomer-specific oriented attachment, an essential process in Viedma ripening, was also investigated in guanidine carbonate crystals. Simply boiling or shaking powdered racemic guanidine carbonate in saturated solution leads to the formation of large crystalline clusters. These clusters, characterized by solid-state circular dichroism and X-ray powdered diffraction, were found to be nearly homochiral. Enantiomer-specific oriented attachment can be thought of as a mesoscale analogue of conglomerate crystallization

Characterization of Phase I and Glucuronide Phase II Metabolites of 17 Mycotoxins Using Liquid Chromatography—High-Resolution Mass Spectrometry

Routine mycotoxin biomonitoring methods do not include many mycotoxin phase I and phase II metabolites, which may significantly underestimate mycotoxin exposure especially for heavily metabolized mycotoxins. Additional research efforts are also needed to measure metabolites in vivo after exposure and to establish which mycotoxin metabolites should be prioritized for the inclusion during large-scale biomonitoring efforts. The objective of this study was to perform human in vitro microsomal incubations of 17 mycotoxins and systematically characterize all resulting metabolites using liquid chromatography–high-resolution mass spectrometry (LC-HRMS). The results obtained were then used to build a comprehensive LC-MS library and expand a validated 17-mycotoxin method for exposure monitoring to screening of additional 188 metabolites, including 100 metabolites reported for the first time. The final method represents one of the most comprehensive LC-HRMS methods for mycotoxin biomonitoring or metabolism/fate studies

Enantiomer-Specific Oriented Attachment of Guanidine Carbonate Crystals

Oriented attachment, a non-classical crystallization phenomenon, describes the spontaneous self-assembly of adjoining crystals with common crystallographic orientations. Introducing chiral recognition between crystals during oriented attachment enables enantiomer-specificity and the formation of homochiral structures. Herein, we report efficient enantiomer-specific oriented attachment for suspended crystals of guanidine carbonate to form mesoscale homochiral or enantioenriched aggregates under boiling or shaking conditions. These aggregates display polyhedral macrostructures and their chirality was monitored using circular dichroism and polarized light microscopy