Sequence-controlled divergent supramolecular assembly of polyproline helices into metallo-peptide nanoparticles.

The field of peptide based supramolecular biomaterials is fast evolving. These types of constructs have been shown to find applications in the fields of bioimaging, drug delivery and scaffolds for chemical reactions. However, the community typically focuses on the use of two specific classes of structured peptides: α-helices and β-sheets, clearly neglecting a unique peptide secondary structure: the polyproline helix.

Ligand Controls Excited Charge Carrier Dynamics in Metal-Rich CdSe Quantum Dots: Computational Insights.

Small metal-rich semiconducting quantum dots (QDs) are promising for solid-state lighting and single-photon emission due to their highly tunable yet narrow emission line widths. Nonetheless, the anionic ligands commonly employed to passivate these QDs exert a substantial influence on the optoelectronic characteristics, primarily owing to strong electron-phonon interactions. In this work, we combine time-domain density functional theory and nonadiabatic molecular dynamics to investigate the excited charge carrier dynamics of CdSeX QDs (X = HCOO, OH, Cl, and SH) at ambient conditions.

The impact of spatially heterogeneous chemical doping on the electronic properties of CdSe quantum dots: insights from computation.

The introduction of copper (Cu) impurity in semiconductor CdSe quantum dots (QDs) gives rise to unique photoluminescence (PL) bands exhibiting distinctive characteristics, like broad line width, significant Stokes shift, and complex temporal decay. The atomistic origins of these spectral features are yet to be understood comprehensively. We employed multiple computational techniques to systematically study the impact of the spatial heterogeneity of Cu atoms on the stability and photophysical properties, including the emission linewidth of doped QDs under ambient conditions.

Dissociative electron attachment to gold(I)-based compounds: 4,5-dichloro-1,3-diethyl-imidazolylidene trifluoromethyl gold(I).

With the use of proton-NMR and powder XRD (XRPD) studies, the suitability of specific Au-focused electron beam induced deposition (FEBID) precursors has been investigated with low electron energy, structure, excited states and resonances, structural crystal modifications, flexibility, and vaporization level. 4,5-Dichloro-1,3-diethyl-imidazolylidene trifluoromethyl gold(I) is a compound that is a uniquely designed precursor to meet the needs of focused electron beam-induced deposition at the nanostructure level, which proves its capability in creating high purity structures, and its growing importance in other AuIm and AuClB (where x and n are the number of radicals, B = CH, CH, or Br) compounds in the radiation cancer therapy increases the efforts to design more suitable bonds in processes of SEM (scanning electron microscopy) deposition and in gas-phase studies. The investigation performed of its powder shape using the XRPD XPERT panalytical diffractometer based on CoK lines shows changes to its structure with change in temperature, level of vacuum, and light; the sensitivity of this compound makes it highly interesting in particular to the radiation research.

Supramolecular Self-Assembly of Engineered Polyproline Helices.

The ability to rationally design biomaterials to form desired supramolecular constructs presents an ever-growing research field, with many burgeoning works within recent years providing exciting results; however, there exists a broad expanse of promising avenues of research yet to be investigated. As such we have set out to make use of the polyproline helix as a rigid, tunable, and chiral ligand for the rational design and synthesis of supramolecular constructs. In this investigation, we show how an oligoproline tetramer can be specifically designed and functionalized, allowing predictable tuning of supramolecular interactions, to engineer the formation of supramolecular peptide frameworks with varying properties and, consequently, laying the groundwork for further studies utilizing the polyproline helix, with the ability to design desired supramolecular structures containing these peptide building blocks, having tunable structural features and functionalities.

A Reversibly Porous Supramolecular Peptide Framework.

The ability to use bio-inspired building blocks in the assembly of novel supramolecular frameworks is at the forefront of an exciting research field. Herein, we present the first polyproline helix to self-assemble into a reversibly porous, crystalline, supramolecular peptide framework (SPF). This framework is assembled from a short oligoproline, adopting the polyproline II conformation, driven by hydrogen-bonding and dispersion interactions.

Stereochemical Inversion of Rim-Differentiated Pillar[5]arene Molecular Swings.

To investigate the dynamic stereochemical inversion behavior of pillar[5]arenes (P[5]s) in more detail, we synthesized a series of novel rim-differentiated P[5]s with various substituents and examined their rapid rotations by variable-temperature NMR (203-298 K). These studies revealed for the first time the barrier of "methyl-through-the-annulus" rotation (Δ = 47.4 kJ·mol in acetone) and indicated that for rim-differentiated P[5]s with two types of alkyl substituents, the smaller rim typically determines the rate of rotation.

Tiara[5]arenes: Synthesis, Solid-State Conformational Studies, Host-Guest Properties, and Application as Nonporous Adaptive Crystals.

Tiara[5]arenes (T[5]s), a new class of five-fold symmetric oligophenolic macrocycles that are not accessible from the addition of formaldehyde to phenol, were synthesized for the first time. These pillar[5]arene-derived structures display both unique conformational freedom, differing from that of pillararenes, with a rich blend of solid-state conformations and excellent host-guest interactions in solution. Finally we show how this novel macrocyclic scaffold can be functionalized in a variety of ways and used as functional crystalline materials to distinguish uniquely between benzene and cyclohexane.

Functionalization at Will of Rim-Differentiated Pillar[5]arenes.

The development of an efficient synthetic route toward rim-differentiated C-symmetric pillar[5]arenes (P[5]s), whose two rims are decorated with different chemical functionalities, opens up successive transformations of this macrocyclic scaffold. This paper describes a gram-scale synthesis of a C-symmetric penta-hydroxy P[5] precursor, and a range of highly efficient reactions that allow functionalizing either rim at will via, e.g.

A Bimodal, Cationic, and Water-Soluble Calix[4]arene Conjugate: Design, Synthesis, Characterization, and Transfection of Red Fluorescent Protein Encoded Plasmid in Cancer Cells.

A new bimodal fluorescent cationic calix[4]arene (L) conjugate has been synthesized in multiple steps and well characterized by NMR and electrospray ionization-mass spectrometry (ESI-MS) techniques. L has been investigated for its DNA binding ability by various spectroscopy techniques like absorption, fluorescence, and circular dichroism (CD). The formation of L-DNA complex has been confirmed by the gel electrophoresis in the presence of incremental concentration of L.

A Bifunctional Thioether Linked Coumarin Appended Calix[4]arene Acquires Selectivity Toward Cu(2+) Sensing on Going from Solution to SAM on Gold.

A bifunctional calix[4]arene molecule bearing coumarin moiety on the lower rim and thioether moiety on the upper rim (L1), has been synthesized and well characterized by (1)H, (13)C NMR and mass spectrometry. Suitably functionalized coumarin moieties are well suited for selective recognition of various cations and anions. Among the 10 different metal ions studied, only Cu(2+) and Fe(3+) exhibit appreciable changes in the absorption spectra owing to the availability of functional moieties present at both the lower as well as the upper rim of free L1 in acetonitrile solution.

Differentiating phosphates by an Mg(2+) complex of the conjugate of calix[4]arene via the formation of ternary species and causing changes in the aggregation: spectroscopy, microscopy, and computational modeling.

A phenylene diimine capped conjugate of 1,3-calix[4]arene (L) was synthesized and characterized, and its Mg(2+) complex has been isolated and characterized. The chemo sensing ensemble of Mg(2+) bound L provides distinguishable features of response toward phosphates, viz., HPO4(2-), P2O7(4-), and AMP(2-) (Set A) and H2PO4(-), ATP(2-), and ADP(2-) (Set B).

Binding and ratiometric dual ion recognition of Zn(2+) and Cu(2+) by 1,3,5-tris-amidoquinoline conjugate of calix[6]arene by spectroscopy and its supramolecular features by microscopy.

Lower rim amide linked 8-amino quinoline and 8-amino naphthalene moiety 1,3,5-triderivatives of calix[6]arene L1 and L2 have been synthesized and characterized. While the L1 acts as a receptor molecule, the L2 acts as a control molecule. The complexation between L1 and Cu(2+) or Zn(2+) was delineated by the absorption and electrospray ionization (ESI) MS spectra.

Supramolecular complexation of biological phosphates with an acyclic triazolium-linked anthracenyl-1,3-diconjugate of calix[4]arene: synthesis, characterization, spectroscopy, microscopy, and computational studies.

A triazolium-anthracenyl calix[4]arene conjugate (L) was synthesized by methylating the precursor triazole derivative and then characterized. The potential of the cationic L to differentiate nucleoside triphosphates (NTPs) from their mono- and diphosphates was demonstrated. Due to its unique combination of arms with the calix-platform, a fluorescence enhancement was observed for L with all the NTPs, whereas there is no report with such enhancement being exhibited in case of all the NTPs.