Página 1 dos resultados de 396 itens digitais encontrados em 0.006 segundos

Self-assembly of metallosupramolecules directed by (N-H)(2)center dot center dot center dot SCN-M (M = Co, Ni), C-H center dot center dot center dot pi and pi-pi synthons

Takahashi, P. M.; Melo, L. P.; Frem, RCG; Netto, AVG; Mauro, A. E.; Santos, RHA; Ferreira, J. G.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 161-167
ENG
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This work deals with the synthesis, spectroscopic and structural investigation of pyrazolyl complexes of the type trans-[M(NCS)(2)(HPz)(4)] {M=Co (1), Ni (2); HPz=pyrazole}. Single crystal X-ray studies on 1 and 2 reveal the formation of similar supramolecular arrangements derived from self-assembly of monomers linked together through intermolecular N-H center dot center dot center dot SCN hydrogen bonds, C-H center dot center dot center dot pi interactions and pi-pi stacking. (c) 2005 Elsevier B.V. All rights reserved.

Self-assembly of organometallic Pd(II) complexes via CH3 center dot center dot center dot pi interactions: the first example of a cyclopalladated compound with herringbone stacking pattern

de Almeida, E. T.; Mauro, A. E.; Santana, A. M.; Ananias, S. R.; Netto, A. V. G.; Ferreira, J. G.; Santos, R. H. A.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 1394-1398
ENG
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Two binuclear cyclometallated compounds [Pd(C-2,N-dmba)(mu-N-3)](2) (1) and [Pd-2(C-2,N-dmba)(2)(mu-N-3)(mu-Cl)] (2) (dmba = N,N-dimethylbenzylarnine) have been synthesized and characterized by elemental 3 analysis, IR and NMR spectroscopies and single crystal X-ray diffraction crystallography. The ability of CH3 groups to form C(sp(3))-H...pi hydrogen bonds with phenyl rings is responsible for the molecular self-assembly within the crystals of 1 and 2. Compound 1 crystallizes as one-dimensional supramolecular chains whereas the crystal packing of 2 consists of a herringbone of sandwiches composed by two inversely related [Pd-2(C-2,N-dmba)(2)(mu-N-3)(mu-Cl)] molecules. (c) 2007 Elsevier B.V. All rights reserved.

Géis supramoleculares : aspectos químicos e físicos de redes nanofibrilares constituídas por agentes gelificantes baseados em glicosídeos; Supramolecular gels : chemical and physical aspects of fibrillar networks constituted of glicoside-based organogelators

Marlon de Freitas Abreu
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 04/10/2012 PT
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O trabalho versa sobre a síntese de doze gelificantes (LMOGs) e um estudo sobre automontagem supramolecular dos LMOGs na construção de nanofibras. Foram sintetizadas duas séries de compostos derivados do metil 4,6-O-benzilideno-a-D-glicopiranosideo substituído na posição 4 do anel aromático com grupos (G) modificadores de densidade eletrônica, série A (G = n-alcoxil) e série B (G = n-alcoxicarbonil); e dois agentes de reticulação supramolecular (C e D). Fez-se um estudo da supramolecularidade usando várias técnicas. O ensaio de gelificação revelou que os LMOGs da série B enrijecem maior numero de solventes em maior faixa de concentração do que os da série A. A habilidade de gelificação foi destacada nos LMOGs de maior cadeia carbônica. Identificou-se por IV-TF que os LMOGs da série A se agregam por apenas um dos grupos OH, enquanto os LMOGs da série B pelos dois. A MEV mostrou estruturas fibrosas com morfologias cilíndricas e/ou fitas, com o menor diâmetro de 40 nm. Os termogramas no DSC indicaram que a Tgel aumentou com a concentração, porém ela diminuiu com o tamanho da cadeia carbônica em ambas as séries. O UV/vis mostrou que os grupos aromáticos estão arranjados obliquamente e próximos a um empilhamento p. As fibras de ambas as séries apresentaram helicidade P no DC. Observou-se com SAXS que a habilidade de gelificação está relacionada com o crescimento 1D. Os espectros de NOESY confirmam o que foi evidenciado no IV/térmico...

Crystal structure, supramolecular self-assembly and interaction with DNA of a mixed ligand manganese(II) complex

Sun,Yun-Ming; Dong,Feng-Ying; Wang,Da-Qi; Li,Yan-Tuan
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2011 EN
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A mixed ligand manganese(II) complex, [Mn(sal)(phen)2]ClO4 (1) (sal = salicylaldehyde, phen = 1,10-phenanthroline), has been synthesized and characterized by elemental analysis and single crystal X-ray diffractometry. The structural analysis revealed that complex 1 crystallizes in the monoclinic space group P2(1)/n. The asymmetric unit of the complex is comprised of [Mn(sal)(phen)2]+ complex cation and uncoordinated perchlorate anion. The manganese(II) is located in a seriously distorted octahedral MnN4O2 coordination environment. Four types of π-π stacking modes involving phenanthroline and salicylaldehyde ligands are involved in the supramolecular self-assembly. These aromatic stacking interactions cooperate with hydrogen bonding to assemble the complex into a fascinating 3D supramolecular architecture. Electronic absorption spectroscopy and fluorescence titration studies of the interaction between complex 1 and calf thymus DNA suggest an intercalative binding mode with a constant of 7.97×10³ L mol-1 and a Stern-Volmer quenching constant of 1.34×10(4) L mol-1.

Supramolecular polymer formed by reversible self-assembly of tetrakisporphyrin

Haino, Takeharu; Fujii, Takashi; Watanabe, Akihide; Takayanagi, Urara
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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S-shaped tetrakisporphyrin 2 forms supramolecular polymeric assemblies via a complementary affinity of its bisporphyrin units in solution. The self-association constant determined by applying the isodesmic model is >106 L mol−1, which suggests that a sizable polymer forms at millimolar concentrations at room temperature. The electron deficient aromatic guest (TNF) binds within the molecular clefts provided by the bisporphyrin units via a charge-transfer interaction. This guest complexation completely disrupts supramolecular polymeric assembly. The long, fibrous fragments of the polymeric assemblies were characterized by atomic-force microscopy imaging of a film cast on a mica surface. The polymeric assemblies have lengths of >1μm and show a coiled structure with a higher level of organization. The approach discussed in this report concerning the quick preparation of supramolecular polymeric assemblies driven by noncovalent forces sets the stage for the preparation of a previously undescribed class of macromolecular porphyrin architectures.

Multiplexed Supramolecular Self-Assembly For Non-Viral Gene Delivery

Gabrielson, Nathan P.; Cheng, Jianjun
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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Recently, there has been success applying a semi-rational approach to non-viral gene delivery vector development using a combinatorial/parallel synthesis approach to construct libraries of materials with unique molecular structures. In this approach, it is hoped that the random incorporation of various hydrophobic and hydrophilic domains in the library will yield candidates with the appropriate balance of DNA binding strength and endosomolytic properties to yield efficient gene delivery. Herein we describe a library approach to gene delivery vector development that relies on the supramolecular self-assembly of individual components instead of chemical reaction. Each component in the described system is capable of performing a single and well-defined purpose—DNA binding (dioleylspermine), membrane permeation (oligoarginine) or targeting (folic acid). A combination of electrostatic attraction and the hydrophobic effect is used to bring the individual groups together to form nanoscale complexes with DNA. Because the components responsible for DNA binding, membrane permeation and targeting are separate, it is possible to alter the balance between hydrophilic and hydrophobic groups by varying the relative amounts in the final formulation. By doing so...

Bio-inspired supramolecular self-assembly towards soft nanomaterials

LIN, Yiyang; MAO, Chuanbin
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/09/2011 EN
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Supramolecular self-assembly has proven to be a reliable approach towards versatile nanomaterials based on multiple weak intermolecular forces. In this review, the development of bio-inspired supramolecular self-assembly into soft materials and their applications are summarized. Molecular systems used in bio-inspired “bottom-up self-assembly” involve small organic molecules, peptides or proteins, nucleic acids, and viruses. Self-assembled soft nanomaterials have been exploited in various applications such as inorganic nanomaterial synthesis, drug or gene delivery, tissue engineering, and so on.

Self-assembly of 2,3-dihydroxycholestane steroids into supramolecular organogels as a soft template for the in-situ generation of silicate nanomaterials

Edelsztein, Valeria C; Mac Cormack, Andrea S; Ciarlantini, Matías; Di Chenna, Pablo H
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 09/09/2013 EN
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Supramolecular gels are an important and interesting class of soft materials that show great potential for many applications. Most of them have been discovered serendipitously, and understanding the supramolecular self-assembly that leads to the formation of the gel superstructure is the key to the directed design of new organogels. We report herein the organogelating property of four stereoisomers of the simple steroid 2,3-dihydroxycholestane. Only the isomer with the trans-diaxial hydroxy groups had the ability to gelate a broad variety of liquids and, thus, to be a super-organogelator for hydrocarbons. The scope of solvent gelation was analysed with regard to two solvent parameters, namely the Kamlet–Taft and the Hansen solubility parameters. The best correlation was observed with the Hansen approach that revealed the existence of two clear gelation zones. We propose a general model of self-assembly through multiple intermolecular hydrogen bonds between the 1,2-dihydroxy system, which is based on experimental data and computational simulations revealing the importance of the di-axial orientation of the hydroxy groups for the one-dimensional self-assembly. Under controlled conditions, the fibrillar superstructure of the organogel was successfully used as a template for the in-situ sol–gel polymerization of tetraethoxysilane and the further preparation of silica nanotubes. We propose that the driving forces for templating are hydrogen bonding and electrostatic interactions between the anionic silicate intermediate species and the self-assembled fibrillar network.

Complex self-assembly of pyrimido[4,5-d]pyrimidine nucleoside supramolecular structures

Zhao, Hang; Guo, Xiurong; He, Shiliang; Zeng, Xin; Zhou, Xinglong; Zhang, Chaoliang; Hu, Jing; Wu, Xiaohua; Xing, Zhihua; Chu, Liangyin; He, Yang; Chen, Qianming
Fonte: Nature Pub. Group Publicador: Nature Pub. Group
Tipo: Artigo de Revista Científica
Publicado em 24/01/2014 EN
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Supramolecular self-assembly is not only one of the chemical roots of biological structure but is also drawing attention in different industrial fields. Here we study the mechanism of the formation of a complex flower-shaped supramolecular structure of pyrimido[4,5-d]pyrimidine nucleosides by dynamic light scattering, scanning electron microscopy, differential scanning calorimetry, nuclear magnetic resonance and X-ray analysis. Upon removing the hydroxyl group of sugars, different flower-shaped superstructures can be produced. These works demonstrate that complex self-assembly can indeed be attained through hierarchical non-covalent interactions of single molecules. Furthermore, chimerical structures built from molecular recognition by these monomers indicate their potential in other fields if combined with other chemical entities.

A versatile strategy towards non-covalent functionalization of graphene by surface-confined supramolecular self-assembly of Janus tectons

Du, Ping; Bléger, David; Charra, Fabrice; Bouchiat, Vincent; Kreher, David; Mathevet, Fabrice; Attias, André-Jean
Fonte: Beilstein-Institut Publicador: Beilstein-Institut
Tipo: Artigo de Revista Científica
Publicado em 03/03/2015 EN
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Two-dimensional (2D), supramolecular self-assembly at surfaces is now well-mastered with several existing examples. However, one remaining challenge to enable future applications in nanoscience is to provide potential functionalities to the physisorbed adlayer. This work reviews a recently developed strategy that addresses this key issue by taking advantage of a new concept, Janus tecton materials. This is a versatile, molecular platform based on the design of three-dimensional (3D) building blocks consisting of two faces linked by a cyclophane-type pillar. One face is designed to steer 2D self-assembly onto C(sp2)-carbon-based flat surfaces, the other allowing for the desired functionality above the substrate with a well-controlled lateral order. In this way, it is possible to simultaneously obtain a regular, non-covalent paving as well as supramolecular functionalization of graphene, thus opening interesting perspectives for nanoscience applications.

Flower-like supramolecular self-assembly of phosphonic acid appended naphthalene diimide and melamine

Bhosale, Rajesh S; Al Kobaisi, Mohammad; Bhosale, Sidhanath V.; Bhargava, Suresh; Bhosale, Sheshanath V.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 29/09/2015 EN
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Diverse supramolecular assemblies ranging from nanometres to micrometers of small aromatic π-conjugated functional molecules have attracted enormous research interest in light of their applications in optoelectronics, chemosensors, nanotechnology, biotechnology and biomedicines. Here we study the mechanism of the formation of a flower-shaped supramolecular structure of phosphonic acid appended naphthalene diimide with melamine. The flower-shaped assembly formation was visualised by scanning electron microscope (SEM) and transmission electron microscopy (TEM) imaging, furthermore, XRD and DLS used to determined mode of aggregation. Characteristically, phosphonic acid-substituted at imide position of NDIs possess two important properties resulting in the formation of controlled flower-like nanostructures: (i) the aromatic core of the NDI which is designed to optimize the dispersive interactions (π-π stacking and van der Waals interactions) between the cores within a construct and (ii) phosphonic acid of NDI interact with malamine through molecular recognition i.e. strong hydrogen-bonding (H-bonding). We believe such arrangements prevent crystallization and favour the directional growth of flower-like nanostructure in 3D fashion. These works demonstrate that complex self-assembly can indeed be attained through hierarchical non-covalent interactions of two components. Furthermore...

Donor and acceptor molecules on metal surfaces: supramolecular self-assembly, metal-organic coordination networks, and charge-transfer complexes

Rodríguez Fernández, Jonathan
Fonte: Universidade Autônoma de Madrid Publicador: Universidade Autônoma de Madrid
Tipo: Tese de Doutorado
SPA; ENG
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This thesis presents a dissertation on supramolecular self-assembly, coordination networks and charge transfer complexes of four molecules: Dicyanop- quinonediimine (DCNQI), Tetracyanoethylene (TCNE), Tetracyanoquinodimethane (TCNQ) and Tetrathiafulvalene (TTF) at a noble metal surface. Different systems were analyzed by variable temperature scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and the results were compared with theoretical within the density functional theory (DFT). In the first part of this thesis, the adsorption of the individual molecules (TCNE, TCNQ, and TTF) on a Ag(111) surface was studied. The growth of TCNE on Ag(111) results in the formation of two different Ag-TCNE coordination networks, depending on the substrate temperature, where the silver adatoms originate from the step etching of the silver substrate. According to DFT calculations and in agreement with XPS measurements, the TCNE molecules are negatively charged ( 1 e), taking charge from the substrate and from the silver adatom (the charge on the silver adatoms is 0.45 e). The adsorption of TCNQ on Ag(111) shows the formation of three different phases, where the molecules are bonded together by hydrogen bonds...

Multi-Hierarchical Self-Assembly of Collagen Mimetic Peptides into AAB Type Heterotrimers, Nanofibers and Hydrogels Driven by Charged Pair Interactions

O'Leary, Lesley Russell
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text Formato: 258 p.; application/pdf
ENG
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Replicating the multi-hierarchical self-assembly of collagen (peptide chain to triple helix to nanofiber and, finally, to a hydrogel) has long attracted scientists, both from the fundamental science perspective of supramolecular chemistry and for the potential biomedical applications perceived in tissue engineering. In terms of triple helical formation, collagen is the most abundant protein in the human body with at least 28 types, yet research involving collagen mimetic systems has only recently began to consider the innate ability of collagen to control helix composition and register. Collagen triple helices can be homotrimeric or heterotrimeric and while some types of natural collagen form only one specific composition of helix, others can form multiple. It is critical to fully understand and, if possible, reproduce the control that native collagen has on helix composition and register. In terms of nanofiber formation, many approaches to drive the self-assembly of synthetic systems through the same steps as natural collagen have been partially successful, but none have simultaneously demonstrated all levels of structural assembly. In this work, advancements in the ability to control helix composition and replicate the multi-hierarchical assembly of collagen are described. Both positive and negative design for the assembly of AAB type collagen heterotrimers were utilized by promoting heterotrimer formation though the use of charged amino acids to form intra-helix electrostatic interactions...

Self-Assembly of Dinuclear Complexes Featuring Aromatic and Aliphatic Walls

Stevenson, Kristina
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
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The objective of my MSc thesis is to study the self-assembly process of macrocyclic complexes, as well as the properties that affect the obtained supramolecular architectures. The possibility of substrate recognition within the cavity of these complexes is also of interest. Preparation of three new ligands based on the triazole-pyridine chelating units connected through variable spacer groups, as well as the complexes formed with octahedral metal ions, are described herein. The first ligand contained a naphthalene spacer region, which was longer than the previously examined xylene spacer. This extension increases the distance between metal ions in the complex, as well as the size of the cavity. More work is required to obtain the unsaturated double-stranded complex, which could potentially bind substrate molecules within its cavity. The triple-stranded saturated complexes with [Fe(H2O)6](BF4)2 and [Ni(H2O)6](BF4)2 both gave insight into the process of self-assembly. The next two ligands were designed to probe the effect that increasing the length of an aliphatic spacer had on complex self-assembly. Both ethyl and propyl spacer units had been previously studied, so butyl and pentyl spacer groups were the natural next step to analyze. The length of the alkyl spacer was found to be very important in the nature of the obtained complex. As the length of the alkyl chain...

Self-assembly of PS-PVP block copolymers and their complexes at the air/water interface

Perepichka, Iryna I.
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
EN
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Une compréhension approfondie et un meilleur contrôle de l'auto-assemblage des copolymères diblocs (séquencés) et de leurs complexes à l'interface air/eau permettent la formation contrôlée de nanostructures dont les propriétés sont connues comme alternative à la nanolithographie. Dans cette thèse, des monocouches obtenues par les techniques de Langmuir et de Langmuir-Blodgett (LB) avec le copolymère dibloc polystyrène-poly(4-vinyl pyridine) (PS-PVP), seul ou complexé avec de petites molécules par liaison hydrogène [en particulier, le 3-n-pentadécylphénol (PDP)], ont été étudiées. Une partie importante de notre recherche a été consacrée à l'étude d'une monocouche assemblée atypique baptisée réseau de nanostries. Des monocouches LB composées de nanostries ont déjà été rapportées dans la littérature mais elles coexistent souvent avec d'autres morphologies, ce qui les rend inutilisables pour des applications potentielles. Nous avons déterminé les paramètres moléculaires et les conditions expérimentales qui contrôlent cette morphologie, la rendant très reproductible. Nous avons aussi proposé un mécanisme original pour la formation de cette morphologie. De plus, nous avons montré que l'utilisation de solvants à haut point d’ébullition...

Expanding the Solvent Chemical Space for Self-Assembly of Dipeptide Nanostructures

Mason, Thomas O.; Chirgadze, Dimitri Y.; Levin, Aviad; Adler-Abramovich, Lihi; Gazit, Ehud; Knowles, Tuomas P. J.; Buell, Alexander K.
Fonte: ACS Publicador: ACS
Tipo: Article; accepted version
EN
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This is the accepted manuscript for a paper published in ACS Nano, 2014, 8 (2), pp 1243?1253 DOI: 10.1021/nn404237f , Publication Date (Web): January 14, 2014; Nanostructures composed of short, noncyclic peptides represent a growing field of research in nanotechnology due to their ease of production, often remarkable material properties, and biocompatibility. Such structures have so far been almost exclusively obtained through self-assembly from aqueous solution, and their morphologies are determined by the interactions between building blocks as well as interactions between building blocks and water. Using the diphenylalanine system, we demonstrate here that, in order to achieve structural and morphological control, a change in the solvent environment represents a simple and convenient alternative strategy to the chemical modification of the building blocks. Diphenylalanine (FF) is a dipeptide capable of self-assembly in aqueous solution into needle-like hollow micro- and nanocrystals with continuous nanoscale channels that possess advantageous properties such as high stiffness and piezoelectricity and have so emerged as attractive candidates for functional nanomaterials. We investigate systematically the solubility of diphenylalanine in a range of organic solvents and probe the role of the solvent in the kinetics of self-assembly and the structures of the final materials. Finally...

Data for journal article "Electrostatically-directed self-assembly of ultra-thin supramolecular polymer microcapsules" published in 'Advanced Functional Materials'. DOI: 10.1002/adfm.201501079

Parker, Richard M.; Zhang, Jing; Zheng, Yu; Coulston, Roger J.; Smith, Clive A.; Salmon, Andrew R.; Yu, Ziyi; Scherman, Oren A.; Abell, Chris
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Relatório Formato: Metadata: PDF. Data is provided in zipped folders, containing the following file types: Images: JPG and TIF. Numerical data: XLSX (also saved as PDF) and TXT. Spectra: PDF. Total file size 10.1 MB
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Supporting data for the article titled "Electrostatically-directed self-assembly of ultra-thin supramolecular polymer microcapsules". The article was accepted for publication on 28th April 2015 in the journal "Advanced Functional Materials". Electronic supporting Information is available from the publisher (Wiley). This data provides the original confocal fluorescence micrographs and the corresponding spreadsheets used to generate the line-graphs included in Figures 2 and 4 in the manuscript, and S5 in the Electronic supporting Information. The processed spreadsheet, hyperspectral cube dataset and optical micrographs used in 2-dimensional thickness mapping of the microcapsule, as reported in Figure 3 of the manuscript, is also included. NMR and IR spectra are in the "synthesis and characterisation" folder.; The Author Accepted Manuscript version of the journal article is available at https://www.repository.cam.ac.uk/handle/1810/248260. The published version is at http://onlinelibrary.wiley.com/doi/10.1002/adfm.201501079/abstract; This work was supported by the ERC, EPSRC, and Isaac Newton Trust

Self-assembly of synthetic and biological components in water using cucurbit[8]uril

Zayed, Jameel Majed
Fonte: University of Cambridge; Department of Chemistry Publicador: University of Cambridge; Department of Chemistry
Tipo: Thesis; not applicable; doctoral; PhD Formato: Digital copy of the submitted hard-bound thesis
EN
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This thesis discusses progress made towards assembling molecular building blocks in the presence of our molecular host of choice, cucurbit[8]uril (CB[8]). Our studies on the self-assembly of synthetic and biological components in water bridge overlapping concepts and techniques drawn from the fields of synthetic organic chemistry, supramolecular self-assembly, and applied NMR techniques. Chapter 1 introduces the reader to chemical complexity, and how supramolecular chemists have advanced in their capability of assembling more complex molecular architectures. The discussion focusses particularly on self-assembly carried out in the aqueous phase, and how, like in biology, molecular design of the building blocks become critical in enabling non-covalent assembly to occur in this dynamic, and relatively competitive environment. The cucurbit[n]uril family of molecular hosts are then introduced with an overview of their modes of binding, and affinities towards typical guests. Finally, a practical introduction to NMR methods gaining prominence in supramolecular chemistry is presented. In particular, the use of diffusion NMR, a key tool for probing the solution dynamics of molecular assemblies, is highlighted. Chapter 2 details work carried out on the CB[8]-mediated self-assembly of supramolecular block copolymers from polymeric...

Self-assembly of supramolecular platinum complexes with bis-4-pyridyl cavitands

Jude, Hershel; Sinclair, David; Das, Neeladri; Sherburn, Michael; Stang, Peter J
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
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The design and self-assembly of six new supramolecular complexes (four triangles and two 2+2 assemblies) are described. These assemblies incorporate two new bispyridyl cavitand building blocks and were prepared in excellent yields (85-95%). The assemblies and building blocks were characterized with multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. Isotopically resolved mass spectrometry along with NMR data confirms the existence of the six assemblies.

Critical self-assembly concentration of bolaamphiphilic peptides and peptide hybrids determined by fluorescence measurements

Martari,Marco; Sanderson,Ronald D.
Fonte: South African Journal of Chemistry Publicador: South African Journal of Chemistry
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2008 EN
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The study of the self-assembly properties of peptides and proteins is important for the understanding of molecular recognition processes and for the rational design of functionalbiomaterials. Novel bolaamphiphilic peptides and peptide hybrids incorporating non-natural aminoacids were designed around a model lysine/leucine-rich peptide with the intention to study their self-assembly behaviour. Steady-state fluorescence measurements using pyrene as fluorescent probe were adapted to the determination of the critical self-assembly concentrations (CSACs) of these amphiphilic peptides and peptide hybrids. Different experimental conditions were studied. The morphology of the peptide aggregates was evaluated by scanning electron microscopy (SEM). Concentration and pH have been revealed to play a key role in the control of the process. Peptides presented different three-dimensional supramolecular arrangements that were correlated with their aminoacid compositions (specifically considering the presence of tyrosine and proline) and CSAC values.