13221-98-2Relevant academic research and scientific papers
Acyclic cucurbituril featuring pendant cyclodextrins
Cheng, Ming,Isaacs, Lyle
, p. 53 - 62 (2021)
Acyclic cucurbit[n]uril–β-cyclodextrin chimeric host H1 is presented. The goal of the study is to deepen the cavity of the receptor to allow β-CD complexation of moieties on the guest (especially fentanyl) that protrude from the cavity to enhance binding affinity and deliver new supramolecular antidotes for fentanyl intoxication. 1H NMR spectroscopy was used to deduce the geometry of the complexes between H1 and H2 and the guest panel whereas isothermal titration calorimetry was used to determine the thermodynamic parameters of complexation. Hosts H1 and H2 retain the essential molecular recognition features of CB[n] receptors, but H1 binds slightly stronger towards the guest panel than H2. Compared to tetraanionic M1 and M2, dianionic H1 and H2 are less potent receptors which reflects the importance of electrostatic interactions in this series of hosts. The work highlights the challenges inherent in the optimisation of binding affinity of hosts as potential supramolecular antidotes.
Designing the synthesis of catalytically active Ti-β by using various new templates in the presence of fluoride anion
Sasidharan, Manickam,Bhaumik, Asim
experimental part, p. 16282 - 16294 (2012/01/14)
Crystallization of large-pore Ti-β by using a variety of diquaternary ammonium derivatives of dibromoalkane and amines such as triethylamine, 1,4-diazabicyclo[2,2,2]octane (DABCO), and quinuclidine as structure-directing agents (SDA) is described. The size of hydrophobic bridging alkyl-chain length of the template [R3N+-(CH2)x-N +R3](OH-)2 directs the final crystalline product: Ti-β, Ti-ZSM-12, Ti-nonasil or Ti-ZSM-5, as x gradually changes from 6 to 1, in the fluoride medium under hydrothermal conditions. A dense phase such as Ti-nonasil (clathrasil type) is crystallized as the size of hydrophobic bridging alkyl-chain length decreases. The use of F- anions as a mineralizer and Ti4+ as a heteroatom in the synthesis gel also influences the selectivity of final crystalline product. The phase purity and incorporation of Ti4+ into the lattice of β (BEA) and ZSM-12 frameworks are confirmed using XRD, UV-visible, FT-IR, 29Si NMR spectroscopes, elemental analysis (ICP), surface area measurements and catalytic test reactions. The morphology of Ti-β samples is dependent on the nature of the structure-directing agent as revealed by the scanning electron microscopic (SEM) observations. The catalytic activity in the epoxidation of 4-vinyl-1-cyclohexene is increased with the amount of tetrahedral Ti4+ atoms in the framework. The new templates can be effectively used for preparation of catalytically active Ti-β with the minimum number of framework defect sites.
