A comparative study of crystal structures and inclusion properties of fluorinated triazines

Three perfluorinated host compounds of the triazine type, namely 2,4,6-tris(pentafluorophenoxy)-1,3,5-triazine (1), 2,4,6-tris(pentafluorothiophenoxy)-1,3,5-triazine (2) and 2,4,6-tris(pentafluorophenamin)-1,3,5-triazine (3), were synthesized differing only in the linking heteroatom (O, S and NH) between the triazine core and the pentafluorophenyl groups. The crystal structures involving compounds 1, 2 and their inclusion compounds are dominated by a variety of fluorine interactions (phenyl-perfluorophenyl, C-H?F, F?F, C-F?π_F). However, in the structure of 3, possessing additional hydrogen atoms of the linkage NH-groups, the formation of hydrogen bonds is favoured, whereas fluorine contacts are less apparent. Investigations by powder X-ray diffraction and thermogravimetric analysis revealed substantial differences in the host-guest interactions of the inclusion compounds.     

Sulfated and Non‐Sulfated Glycopeptide Recognition Domains of P‐Selectin Glycoprotein Ligand 1 and their Binding to P‐ and E‐Selectin

Total synthesis through block glycosylation and selective chemical O‐sulfation of tyrosine residues yielded the glycopeptide recognition domain A (X=SO₃^?) of the P‐selectin glycoprotein ligand 1, in which the terminal sialic acid of the complex hexasaccharide side chain was replaced by (S)‐cyclohexyl lactic acid. In binding assays the O‐sulfated structure A showed high affinity towards P‐selectin, the non‐sulfated towards E‐selectin.

     

Sustainable synthesis and automated deposition: an accessible discovery screening library of fragment-like purines

A sub-library of 88 information-rich lead-like purine derivatives were prepared and deposited in an open access academic screening facility. The rationale for the synthesis of these rigid low complexity structures was the privileged character of the purine heterocycle associated with its inherent probability of interactions with multiple adenine-related targets. Although generally expected to be weak binders in many assays, such fragment-like compounds are estimated to match diverse binding sites. It is suggested that heterocycles with many anchor points for hydrogen bonds can be anticipated to undergo very specific interactions to produce more negative enthalpies and thus provide superior starting points for lead optimization than compounds that owe their activity to entropic effects. The in vitro cytotoxicity of the small compounds on a panel of human cancer cell lines has been investigated and some of them showed marked unselective or selective toxicity. This data may be useful if these fragments are to be incorporated into drug-like structures via metabolically cleavable connections. The sub-library will be implemented as part of the ChemBioNet ( www.chembionet.info ) library, and it is open to screening campaigns of academic research groups striving for a fragment-based approach in their biological assays.     

ChemInform Abstract: Stoichiometry and Structure of Uranyl(VI) Hydroxo Dimer and Trimer Complexes in Aqueous Solution.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Polymers designed to control nucleation and growth of inorganic crystals from aqueous media

Water soluble graft polymers prepared by copolymerization of either methacrylic acid (MAA) or vinylsulfonic acid (VS) with α‐methoxy‐ω‐methacroyl‐oligo(oxyethylene)s (PEO_n‐MA) serve to control nucleation and crystal growth during precipitation of inorganic crystals from aqueous media. Precipitation of zinc oxide crystals (‘zincite’) is used as example for such mineralization processes. Homogeneous and narrow crystal size distributions are obtained in presence of ppm‐amounts of graft copolymers. Copolymer is incorporated into the crystals demonstrated by using latex particles with ‐CO₂H‐group rich surfaces as controlling additives. Incorporation of these particles leads to single crystals with pores of the size of the particles (‘Swiss cheese’ morphologies).     

Mucin-Inspired Single-Chain Polymer (MIP) Fibers as Potent SARS-CoV-2 Inhibitors

Mucins are the key component of the defensive mucus barrier. They are extended fibers of very high molecular weight with diverse biological functions depending strongly on their specific structural parameters. Here, we present a mucin-inspired nanostructure, produced via a synthetic methodology to prepare methacrylate-based dendronized polysulfates ( MIP-1 ) on a multi gram-scale with high molecular weight (MW=450 kDa) and thiol end-functionalized mucin-inspired polymer ( MIP ) via RAFT polymerization. Cryo-electron tomography (Cryo-ET) analysis of MIP-1 confirmed a mucin-mimetic wormlike single-chain fiber structure (length=144±59 nm) in aqueous solution. This biocompatible fiber showed promising activity against SARS-CoV-2 and its mutant strain, with a remarkable low half maximal (IC₅₀) inhibitory concentration (IC₅₀=10.0 nM). Additionally, we investigate the impact of fiber length on SARS-CoV-2 inhibition by testing other functional polymers ( MIPs ) of varying fiber lengths.     

Cyclic and Macrocyclic Molecules Containing Silicon or Tin – Synthesis of Highly Rigid,Potentially Lewis-Acidic Cryptands

Herein we report the syntheses of highly rigid silicon- and tin-containing cyclic and bicyclic compounds with unsaturated organic backbones. The syntheses proceed via di-lithiated diethynylbenzene derivatives. The protocols for the known precursor compounds were significantly improved in a two-step one-pot reaction with yields up to 45 % by alternating addition of the lithiation reagent and starting material. A total of ten compounds were synthesized and the molecular structure in the solid state was elucidated for six novel compounds. Host-guest-experiments with selected molecules were conducted to investigate on the potential of the complexation of small anions. All compounds were characterized by multinuclear NMR spectroscopy and elemental analyses or mass spectrometry and in most parts by SC-XRD analyses.     

Versatile Production of Multivariate,Hyperdimensional End Group and Main Chain Functionalized Polyolefins

The (stereoselective) living coordinative copolymerization of 1-alkenes with 4-aryl-1,6-heptadienes, in both the absence and presence of multiple equivalents of a reversible chain transfer agent, is established as a highly versatile strategy for production of multivariate hyperdimensional functionalized semi-crystalline or amorphous polyolefins that optionally possess either mono- or difunctionalized (telechelic) end-groups in combination with a programmable level of incorporation of orthogonal functional groups within the main-chain. The non-conjugated diene comonomers are readily obtained from a diverse range of aryl carboxaldehyde precursors through a one-step bis-allylation process. These results serve to provide a new platform for exploring the science and technology of a vast new landscape of functionalized classes of polyolefins that are now accessible in practical and scalable quantities.     

Cooperative Network Formation via Two-Colour Light-Activated λ-Orthogonal Chromophores

Independently addressing photoreactive sites within one molecule with two colours of light is a formidable challenge. Here, we combine two sequence independent λ-orthogonal chromophores in one heterotelechelic dilinker molecule, to exploit their disparate reactivity utilizing the same reaction partner, a maleimide-containing polymer. We demonstrate that polymer network formation only proceeds if two colours of light are employed. Upon single colour irradiation, linker-decorated post-functionalized polymers are generated at either wavelength and in either sequence. Network formation, however, is only achieved by sequential or simultaneous two colour irradiation. The herein introduced photoreactive system demonstrates the power of wavelength orthogonal chemistry in macromolecular synthesis.