Suchergebnisse

The database of prospective zeolites (www. hypotheticalzeolites.net) has been screened in search of feasible zeolites. Previous criteria of zeolite feasibil- ity have been reviewed, based on descriptors such as energy, density, average and distribution of ring sizes, and more importantly that of Li et al. (LID criteria) presented recently [Angew. Chem. Int. Ed. 2013, 52, 1673], based on Si O, O . O, and Si . Si distances of SLC-minimised struc- tures. In spite of the still large number of feasible zeolites according to this and other criteria, a number of research- ers wonder why there are so many feasible and so few synthesised zeolites. Without answering this difficult question, a new criteria is proposed in this study based on the fact that T . T . T angles (T is tetrahedral atom) show spe- cific ranges of values depending on the ring size to which they belong. Based on improved definitions to count and enumerate rings in zeolites, and with data from the IZA database, we introduce the TTT criteria, which we propose to use after the LID criteria, to further narrow the space of feasible zeolites. ; We thank ASIC computational centre of UPV for making available their computational resources. UPV is acknolwdeged by funding through project PAID-05-12. G. S. thanks the Spanish government for the provision of Severo Ochoa project (SEV 2012-0267) and MAT2012-31657 project. Professors Mike Treacy and Christian Baerlocher are gratefully acknowledged for useful discussions. Laurent Baumes is thanked by initial training with the database. ; Liu, X.; Valero Cubas, S.; Argente Villaplana, E.; Botti Navarro, VJ.; Sastre Navarro, GI. (2015). The importance of T . T . T angles in the feasibility of zeolites. Zeitschrift fur Kristallographie. Crystalline materials. 230(5):291-299. https://doi.org/10.1515/zkri-2014-1801 ; S ; 291 ; 299 ; 230 ; 5

The genus Thymus, belonging to Lamiaceae family, is rich in medicinal and aromatic species and well-known by several health promoting activities [1,2]. Despite this genus has been extensively studied, some species remain unexploited. In this study, Thymus herba-barona, Thymus pseudolanuginosus and Thymus caespititius decoctions were screened for their phenolic constituents by ultra-high performance liquid chromatography coupled to diode array detector and an electrospray mass spectrometer (UHPLC-DAD-ESI-MSn) operating in negative mode. The three aqueous extracts were rich in caffeic acid derivatives, mainly rosmarinic acid (MW 359) and its structural isomers, that accounted for 55.8 ± 2.8 mg/g in T. herba-barona and 40.2 ± 0.9 and 43.2 ± 3.2 mg/g in T. pseudolanuginosus and T. caespititius, respectively. In turn, other depsides were differently distributed in the three Thyme extracts: while dihydro-salvianolic acid B (MW 716 Da) and caffeoyl rosmarinic acid were particularly representative in T. herba-barona, salvianolic acids K ([M-H]− at m/z 555 493 359) and B ( [M-H]− at m/z 717 519 475) were found in moderate amounts in T. caespititius extract. On the other hand, T. pseudolanuginosus was clearly distinguished by its richness in the flavone luteolin-O-glucuronide ([M − H]− at m/z 461→285). Overall, this work is an important contribution for the phytochemical characterization of these three Thymus species, which are poorly explored. ; The authors acknowledge FCT the European Union, QREN, FEDER, COMPETE, for funding the Organic Chemistry Research Unit (QOPNA) (project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296) ; info:eu-repo/semantics/publishedVersion