Search results for "Molecular chemistry"
showing 10 items of 1103 documents
Indanedione based binary chromophore supramolecular systems as a NLO active polymer composites
2010
Novel route to obtain EO material is proposed by supramolecular assembly of neutral-ground-state (NGS) and zwitterionic (ZWI) NLO chromophores in binary chromophore organic glass (BCOG) host–guest system. On a basis of our Langeven Dynamics (LD) molecular modeling combined with quantum chemical calculations, we have shown that anticipated enhancement NLO efficiency of BCOG material is possible via electrostatic supramolecular assembly of NGS with ZWI chromophore in antiparallel manner. Binding energy of such complex could be more dependent on molecular compatibility of components and local (atomic) charge distribution, then overall molecular dipole moments. According to our LD simulations t…
Polymeric gegenions induced variability and mobility of amphiphilic supramolecular structures on solid substrates
1992
Abstract The micromorphological variations of amphiphilic L -glutamate derivatives at air-substrate interfaces due to an adjacent mobile polymer matrix have been investigated via fluorescence microscopy. Adjusted monolayers of the L -glutamate derivatives have been transferred by LB technique out of different aggregation states onto various substrates. The substrates have been prepared by successive polymer preadsorption to the solid support. The influence of the adjacent polymer layers on the domain morphology as a function of water content and temperature has been examined intensively. Moreover, reversible domain changes induced by temperature variation of the transferred films have been …
Light-Fueled, Spatiotemporal Modulation of Mechanical Properties and Rapid Self-Healing of Graphene-Doped Supramolecular Elastomers
2017
Gaining spatially resolved control over the mechanical properties of materials in a remote, programmable, and fast-responding way is a great challenge toward the design of adaptive structural and functional materials. Reversible, temperature-sensitive systems, such as polymers equipped with supramolecular units, are a good model system to gain detailed information and target large-scale property changes by exploiting reversible crosslinking scenarios. Here, it is demonstrated that coassembled elastomers based on polyglycidols functionalized with complementary cyanuric acid and diaminotriazine hydrogen bonding couples can be remotely modulated in their mechanical properties by spatially conf…
Highly Defined, Colloid‐Like Ionic Clusters in Solution
2012
Many societal challenges at the beginning of the 21st century lead to an apparent and growing need for functional materials and novel ways of materials synthesis and assembly. Rising to the challenge, the utilization of small, self-assembling building blocks for the bottom-up construction of new types of polymers and nanostructures has enjoyed increasing popularity among materials researchers in the recent past. Supramolecular materials like foldamers, surface films, nanoparticles, etc. are created by exploiting noncovalent forces [1] leading to an ordered arrangement of nanoscale building blocks. [2] In the search for new polymers based on noncovalent molecular forces, we are motivated by …
From Bowls to Capsules: Assembly of Hexanuclear Ni II Rings Tailored by Alkali Cations
2020
An anionic hexanuclear NiII metallamacrocycle with endo and exo linking sites has been employed as a building block to generate a series of capsules and bowls of nanometric size. The supramolecular arrangement of the {Ni6 } rings was tailored by the size of the alkali cations, showing the transition from {Ni6 -M2 -Ni6 } capsules (M=LiI and NaI ) to {Ni6 -M} bowls (M=KI and CsI ). The alkyl co-cations are determinant to stabilize the assemblies by means of CH⋅⋅⋅π interactions on the exo side of the metallamacrocycles. The effect on the topology of the supramolecular assemblies of the cation size, cation charge, Et3 NH+ or Me4 N+ counter cations has been analyzed. Magnetic measurements reveal…
Synthesis of all-syn Functionalized Triphenylene Ketals
2011
The stereoselective synthesis of triphenylene ketals offers access to unique scaffolds. For a good performance in supramolecular applications an all-syn orientation of the functional groups is essential. The oxidative trimerization of catechol ketals by molybdenum pentachloride or mixtures with titanium tetrachloride leads to a template-directed formation. Several heterocyclic moieties are suitable for this transformation. A template-directed isomerization of anti,anti,syn isomers to the desired C 3 -symmetric derivative was demonstrated in two cases.
Synthesis and Characterization of theO-Alkylation Products of Resorcinarene
2013
O-Substitution reactions of tetramethoxyresorcinarene with alkyl halides produced a variety of partially O-alkylated resorcinarene derivatives with terminal alkyne functionality. The degree of alkylation was affected by the reactivity of the alkylating halide used. NMR spectroscopy proved to be an ideal tool for analyzing the complex reaction mixtures and the isolated products based on the symmetry and degree of alkylation of the resorcinarene derivatives. Single-crystal X-ray diffraction studies furthermore showed diversity in the self-assembly of the various O-alkylation products that was greatly affected by the degree of alkylation, as well as the nature of the alkyne moiety.
Synthesis and characterisation of tetrazole compounds: 3 series of new ligands representing versatile building blocks for iron(II) spin-crossover com…
2005
Abstract New tetrazole compounds were synthesized and characterised by NMR and FTIR spectroscopy as well as by single crystal X-ray diffraction. We present in this paper mono- and ditetrazoles, which represent a versatile class of building blocks for the formation of mononuclear iron(II) complexes with monotetrazoles as terminal ligands as well as iron(II) coordination polymers with ditetrazoles as bridging ligands. Especially, the series of α,ω-bis[tetrazol-1-yl]-alkanes open the field of fascinating supramolecular structures with spin transition properties.
Halogen bonding enhances nonlinear optical response in poled supramolecular polymers
2015
We demonstrate that halogen bonding strongly enhances the nonlinear optical response of poled supramolecular polymer systems. We compare three nonlinear optical chromophores with similar electronic structures but different bond-donating units, and show that both the type and the strength of the noncovalent interaction between the chromophores and the polymer matrix play their own distinctive roles in the optical nonlinearity of the systems. acceptedVersion Peer reviewed
Pollutant Adsorbtion and Detection: Methyl-Substituted α-Cyclodextrin as Affinity Material for Storage, Separation, and Detection of Trichlorofluorom…
2018
The cover image depicts the hazard caused by chlorofluorocarbons such as CFC‐11, which are used, for example, as blowing agents for polyurethane foams, and the protective effect of the oligosaccharide, hexakis‐(2,3,6‐tri‐O‐methyl)‐α‐cyclodextrin, which is capable of binding CFC‐11 by supramolecular complexation and thus protecting the stratospheric ozone layer from the harmful trichlorofluoromethane. Further details can be found in article number 1800057 by Ralf Hellmann, Siegfried R. Waldvogel, and co‐workers.