21 results on '"Amabilino, David B."'
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2. How Deformation Can Lend a Hand to Molecular Ordering
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Amabilino, David B.
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- 2009
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3. Chirality from scratch: enantioselective adsorption in geometrically controlled lateral nanoconfinement.
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Seibel, Johannes, Tessari, Zeno, Amabilino, David B., and De Feyter, Steven
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CHIRALITY of nuclear particles ,PYROLYTIC graphite ,ADSORPTION (Chemistry) ,CHIRALITY ,SYMMETRY breaking ,LITHOGRAPHY - Abstract
Chiral symmetry breaking in molecular adsorption at the solid/liquid interface by lateral geometric nanoconfinement is demonstrated. The chiral nanoconfinement is created at the interface of achiral covalently modified highly-oriented pyrolytic graphite and a racemate by in situ scanning probe lithography. Enantioselective adsorption of chiral molecules is achieved by adjusting the relative orientation between the nanoconfining walls and substrate symmetry direction. [ABSTRACT FROM AUTHOR]
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- 2021
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4. Self‐Assembly of Chiral‐at‐End Diketopyrrolopyrroles: Symmetry Dependent Solution and Film Optical Activity and Photovoltaic Performance.
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Hume, Paul A., Monks, James P., Pop, Flavia, Davies, E. Stephen, MacKenzie, Roderick C. I., and Amabilino, David B.
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MOLECULAR self-assembly ,CHIRALITY ,PYRROLES ,SYMMETRY (Physics) ,SOLUTION (Chemistry) ,OPTICAL rotation ,PHOTOVOLTAIC cells - Abstract
Abstract: Chiral thiophene‐diketopyrrolopyrrole derivatives have been synthesised to investigate the potential of stereochemistry and symmetry as a means of modulating properties by influencing self‐assembly of these purely organic materials. In particular, derivatives of diketopyrrolopyrrole were employed because of their proven interest as dyes, especially for organic solar cells. The natural product myrtenal was used as the source of stereochemistry, introduced through a Kröhnke reaction of a thiophene‐bearing pyridinium salt and diketopyrrolopyrroles were prepared through Suzuki coupling with this chiral moiety at one end only as well as at both ends. Absorption spectroscopy and electrochemistry confirmed the potential suitability of the compounds for photovoltaic devices. The nanostructures formed by the compounds have been probed with circular dichroism spectroscopy in solution and in films. It is shown that a chiral C
2 symmetric molecule assembles in solution giving a strong circular dichroic signal while as a film this optical activity is nulled, whereas an asymmetric homologue is most optically active as a thin film. The X‐ray crystal structure of the asymmetric compound shows a polar order of the molecules that might explain this observation. The lack of optical activity in solution is very likely a result of the high solubility of the compound. The results reaffirm the sensitivity of circular dichroism spectroscopy to inter‐chromophore organisation, whereas absorption spectroscopy in the visible region reveals only slight changes to the bands. The differing order in the compounds also affects their performance in bulk heterojunction photovoltaic devices. Atomic force microscopy of the blended thin films with the fullerene derivative usually employed (PC61 BM) showed that smooth and well mixed films were achieved, with the conditions required during spin coating depending greatly on the derivative, because of their differing solubility. The apparently better performance of the symmetrical compound (although with very low efficiency) is probably a result of the alignment of the molecules inferred by the circular dichroism experiments, whereas the asymmetric compound presumably adopts a twisted supramolecular organisation. [ABSTRACT FROM AUTHOR]- Published
- 2018
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5. Boosting Self‐Assembly Diversity in the Solid‐State by Chiral/Non‐Chiral ZnII‐Porphyrin Crystallization.
- Author
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Qian, Wenjie, González‐Campo, Arántzazu, Pérez‐Rodríguez, Ana, Rodríguez‐Hermida, Sabina, Imaz, Inhaz, Wurst, Klaus, Maspoch, Daniel, Ruiz, Eliseo, Ocal, Carmen, Barrena, Esther, Amabilino, David B., and Aliaga‐Alcalde, Núria
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PORPHYRINS ,CHIRALITY ,SOLVENTS ,METALLOPORPHYRINS ,SUPRAMOLECULAR chemistry - Abstract
Abstract: A chiral Zn
II porphyrin derivative 1 and its achiral analogue 2 were studied in the solid state. Considering the rich molecular recognition of designed metalloporphyrins 1 and 2 and their tendency to crystallize, they were recrystallized from two solvent mixtures (CH2 Cl2 /CH3 OH and CH2 Cl2 /hexane). As a result, four different crystalline arrangements (1 a,b and 2 a,b, from 0D to 2D) were obtained. Solid‐state studies were performed on all the species to analyze the role played by chirality, solvent mixtures, and surfaces (mica and HOPG) in the supramolecular arrangements. By means of combinations of solvents and substrates a variety of microsized species was obtained, from vesicles to flower‐shaped arrays, including geometrical microcrystals. Overall, the results emphasize the environmental susceptibility of metalloporphyrins and how this feature must be taken into account in their design. [ABSTRACT FROM AUTHOR]- Published
- 2018
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6. Localized Crystallization of Enantiomeric Organic Compounds on Chiral Micro-patterns from Various Organic Solutions.
- Author
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Lingenfelder , Magalí, Bejarano‐Villafuerte , Ángela, van der Meijden, Maarten W., Kellogg, Richard M., and Amabilino, David B.
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CRYSTALLIZATION ,ENANTIOMERS ,ORGANIC compounds ,ORGANIC solvents ,ISOPROPYL alcohol - Abstract
The controlled crystallization of enantiomers of an organic compound (a cyclic phosphoric acid derivative) on templated micro-patterned functionalised surfaces is demonstrated. Areas where a complementary chiral thiol has been located were effective heterogeneous nucleation centres when a solution of the compound is evaporated slowly. Various organic solvents were employed, which present a challenge with respect to other examples when water is used. The solvent and the crystallization method have an important influence on the crystal growth of these compounds. When chloroform was employed, well-defined crystals grow away from the surface, whereas crystals grow in the plane from solutions in isopropanol. In both cases, nucleation is confined to the polar patterned regions of the surface, and for isopropanol growth is largely limited within the pattern, which shows the importance of surface chemistry for nucleation and growth. The apparent dependence on the enantiomer used in the latter case could imply stereo-differentiation as a result of short-range interactions (the templating monolayer is disordered, even at the nanometre scale). The size of the pattern of chiral monolayer also determines the outcome of the crystallization; 5 μm dots are most effective. Despite the low surface tension of the samples (relative to the high surface tension of water), differential solvation of the polar and hydrophobic layers of the solvents allows crystallization in the polar regions of the monolayer, therefore the polarity of the regions in which heterogeneous nucleation takes place is indeed very important. Despite the complex nature of the crystallization process, these results are an important step towards to the use of patterned surfaces for heterogeneous selective nucleation of enantiomers. [ABSTRACT FROM AUTHOR]
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- 2014
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7. A Chiral Self-Assembled Monolayer Derived from a Resolving Agent and its Performance as a Crystallization Template for an Organic Compound from Organic Solvents.
- Author
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Bejarano-Villafuerte, Ángela, van der Meijden, Maarten W., Lingenfelder, Magalí, Wurst, Klaus, Kellogg, Richard M., and Amabilino, David B.
- Abstract
A new chiral nonracemic thiol derived from a popular acidic resolving agent that incorporates a cyclic disubstituted phosphate group (phencyphos) has been prepared in enantiomerically pure form. The stereochemistry and absolute configuration were established by performing a single-crystal X-ray structural analysis of a synthetic intermediate. The thiol compound was used for the preparation of self-assembled monolayers (SAMs) on both monocrystalline and polycrystalline metallic gold, which have very different surface roughness. The monolayers were used to promote the nucleation and growth of crystals from nonaqueous solutions of an organic molecule (the parent phencyphos) of similar structure to the compound present in the monolayer. The template layers influence the nucleation and growth of the phencyphos crystals despite the lack of two-dimensional order in the surfaces. Heterogeneous nucleation of phencyphos takes place upon evaporation of either CHCl
3 or isopropanol solutions of the compound on the SAM surfaces, where the evaporation rate merely influences the size and homogeneity of the crystals. The roughness of the surface also plays an important role; the polycrystalline gold produces more homogeneous samples because of the greater number of nucleation sites. Clear evidence for nucleation and growth on the surfaces is shown by scanning electron microscopy. The variation in crystal form achieved by using different surfaces and solvents suggests that the layers are applicable for the preparation of organic crystals from organic solutions. [ABSTRACT FROM AUTHOR]- Published
- 2012
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8. Pasteurian Segregation on a Surface Imaged In Situ at the Molecular Level.
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Xu, Hong, Saletra, Wojciech J., Iavicoli, Patrizia, Van Averbeke, Bernard, Ghijsens, Elke, Mali, Kunal S., Schenning, Albertus P. H. J., Beljonne, David, Lazzaroni, Roberto, Amabilino, David B., and De Feyter, Steven
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- 2012
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9. Spontaneous Deracemization.
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Amabilino, David B. and Kellogg, Richard M.
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CHIRALITY , *ENANTIOMERS , *SYMMETRY (Physics) , *STOCHASTIC analysis , *CHARGE transfer , *INTERMEDIATES (Chemistry) - Abstract
Chirality can emerge spontaneously from racemizing samples in a remarkably efficient manner. The effect results from the stochastic generation of an excess of one enantiomer in the solid and subsequent amplification of the initial material to the bulk. In this review we shall give examples showing how this effect has proved to be an inspiration for the emergence of chirality from chiral materials, and even for the preparation of pharmaceutically important intermediates. While spontaneous deracemization should produce either enantiomer randomly, the kind of system that demonstrates the phenomenon is very prone to the induction of one handedness with extremely small quantities of chiral inducer, which makes the process exploitable in certain cases. This kind of deracemization is the epitome of the origin, transfer and amplification of chirality. [ABSTRACT FROM AUTHOR]
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- 2011
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10. Bernard L. Feringa, Nobel Prize for Chemistry 2016.
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Amabilino, David B., Berova, Nina D., and Caldwell, John
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NOBEL Prize in Chemistry , *CHIRALITY , *MOLECULAR machinery (Technology) , *CHEMISTRY education - Abstract
We congratulate Ben Feringa on the award of the 2016 Nobel Prize for Chemistry [ABSTRACT FROM AUTHOR]
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- 2016
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11. Supramolecular assembly: Nanofibre whirlpools.
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Amabilino, David B.
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CHIRALITY , *FIBERS , *NANOFIBERS , *CIRCULAR dichroism , *MOLECULES , *SUPRAMOLECULAR chemistry - Abstract
The article focuses on the induction of chirality in solutions of supramolecular fibres such as micrometre-length yarns made up of small achiral molecules and held together by non-covalent interactions. A group of researchers revealed that a stirring solution of achiral fibres can cause chirals to aggregate in a macroscopic chiral arrangement that leads to the appearance of a circular dichroism (CD) signal.
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- 2007
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12. ChemInform Abstract: Biomolecules at Interfaces. Chiral, Naturally.
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Gonzalez‐Campo, Arantzazu and Amabilino, David B.
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BIOMOLECULES , *RESOLUTION (Chemistry) , *CHIRALITY , *STEREOCHEMISTRY , *PHASE-transfer catalysis - Abstract
Review: 242 refs. [ABSTRACT FROM AUTHOR]
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- 2014
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13. Milliseconds Make the Difference in the Far-from-Equilibrium Self- Assembly of Supramolecular Chiral Nanostructures.
- Author
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Sorrenti, Alessandro, Rodriguez-Trujillo, Romen, Amabilino, David B., and Puigmartí-Luis, Josep
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MICROFLUIDIC analytical techniques , *CHIRALITY , *SUPRAMOLECULAR chemistry , *PHYSICAL & theoretical chemistry , *NANOSTRUCTURES , *NANOTECHNOLOGY - Abstract
The effect of diffusion-controlled microfluidic conditions in the very initial stages of a far-from-equilibrium self-assembly process on the evolution of aggregate chirality in a multicomponent supramolecular system is shown. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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14. Bottom-Up Hierarchical Self-Assembly of Chiral Porphyrins through Coordination and Hydrogen Bonds.
- Author
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Oliveras-González, Cristina, Di Meo, Florent, González-Campo, Arántzazu, Beljonne, David, Norman, Patrick, Simón-Sorbed, Maite, Linares, Mathieu, and Amabilino, David B.
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MOLECULAR self-assembly , *CHIRALITY , *PORPHYRINS , *COORDINATE covalent bond , *HYDROGEN bonding , *CIRCULAR dichroism , *CHROMOPHORES , *PYRIDINE - Abstract
A series of chiral synthetic compounds is reported that shows intricate but specific hierarchical assembly because of vatying positions of coordination and hydrogen bonds. The evolution of the aggregates (followed by absorption spectroscopy and temperature-dependent circular dichroism studies in solution) reveal the influence of the proportion of stereogenic centers in the side groups connected to the chromophore ring in their optical activity and the important role of pyridyl groups in the self-assembly of these chiral macrocycles. The optical activity spans 2 orders of magnitude depending on composition and constitution. Two of the aggregates show veiy high optical activity even though the isolated chromophores barely give a circular dichroism signal. Molecular modeling of the aggregates, starting from the pyridinezinc( ll) porphyrin interaction and working up, and calculation of the circular dichroism signal confirm the origin of this optical activity as the chiral supramolecular organization of the molecules. The aggregates show a broad absorption range, between approximately 390 and 475 nm for the transitions associated with the Soret region alone, that spans wavelengths far more than the isolated chromophore. The supramolecular assemblies of the metalloporphyrins in solution were deposited onto highly oriented pyrolitic graphite in order to study their hierarchy in assembly by atomic force microscopy. Zero and one-dimensional aggregates were observed, and a clear dependence on deposition temperature was shown, indicating that the hierarchical assembly took place largely in solution. Moreover, scanning electron microscopy images of porphyrins and metalloporphyrins precipitated under out-of-equilibrium conditions showed the dependence of the number and position of chiral amide groups in the formation of a fibrillar nanomaterial. The combination of coordination and hydrogen bonding in the complicated assembly of these molecules-where there is a clear hierarchy for zinc(II)-pyridyl interaction followed by hydrogen-bonding between amide groups, and then van der Waals interactions-paves the way for the preparation of molecular materials with multiple chromophore environments. [ABSTRACT FROM AUTHOR]
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- 2015
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15. Tuning the Supramolecular Chirality of One- and Two-Dimensional Aggregates with the Number of Stereogenic Centers in the Component Porphyrins.
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lavicoli, Patrizia, Hong Xu, Feldborg, Lice N., Linares, Mathieu, Paradinas, Markos, Stafström, Sven, Ocal, Carmen, Nieto-Ortega, Belen, Casado, Juan, López Navarrete, Juan T., Lazzaroni, Roberto, De Feyter, Steven, and Amabilino, David B.
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PORPHYRINS , *CHIRALITY , *MOLECULAR structure , *SUPRAMOLECULAR chemistry , *METHYL groups , *SCANNING tunneling microscopy - Abstract
A synthetic strategy was developed for the preparation of porphyrins containing between one and four stereogenic centers, such that their molecular weights vary only as a result of methyl groups which give the chiral forms. The low-dimensional nanoscale aggregates of these compounds reveal the profound effects of this varying molecular chirality on their supramolecular structure and optical activity. The number of stereogenic centers influences significantly the self-assembly and chiral structure of the aggregates of porphyrin molecules described here. A scanning tunneling microscopy study of monolayers on graphite shows that the degree of structural chirality with respect to the surface increases almost linearly with the number of stereogenic centers, and only one handedness is formed in the monolayers, whereas the achiral compound forms a mixture of mirror-image domains at the surface. In solution, four hydrogen bonds induce the formation of an H-aggregate, and circular dichroism measurements and theoretical studies indicate that the compounds self-assemble into helical structures. Both the chirality and stability of the aggregates depend critically on the number of stereocenters. The chiral porphyrin derivatives gelate methylcyclohexane at concentrations dependent on the number and position of chiral groups at the periphery of the aromatic core, reflecting the different aggregation forces of the molecules in solution. Increasing the number of stereogenic centers requires more material to immobilize the solvent, in all likelihood because of the greater solubility of the porphyrins. The vibrational circular dichroism spectra of the gels show that all compounds have a chiral environment around the amide bonds, confirming the helical model proposed by calculations. The morphologies of the xerogels (studied by scanning electron microscopy and scanning force microscopy) are similar, although more fibrous features are present in the molecules with fewer stereogenic centers. Importantly, the presence of only one stereogenic center, bearing a methyl group as the desymmetrizing ligand, in a molecule of considerable molecular weight is enough to induce singlehanded chirality in both the one and two-dimensional supramolecular self-assembled structures. [ABSTRACT FROM AUTHOR]
- Published
- 2010
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16. Self-assembly of a chiral porphyrin at surfaces
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Iavicoli, Patrizia, Linares, Mathieu, Pérez del Pino, Ángel, Lazzaroni, Roberto, and Amabilino, David B.
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EVAPORATION (Chemistry) , *MOISTURE , *NATIVE element minerals , *GRAPHITE - Abstract
Abstract: Evaporation of solutions of a new synthetic tetra meso-amidophenyl-substituted porphyrin derivative on graphite leads to different morphologies at the air–solid interface, whose nature depends on the solvent in which the molecule was dissolved. Fibres–which were shown to be a stable aggregate form of the compound by molecular modelling–are observed by AFM, although they do not seem to have the structure which was predicted. The reason for this situation appears to be the dominance of surface–molecule interactions over those between the molecules themselves. On mica surfaces, dewetting takes place, leading to relatively well-defined monolayer and bilayer domains. [Copyright &y& Elsevier]
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- 2008
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17. From purely organic to metallo-organic chiral magnetic materials
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Minguet, Maria, Luneau, Dominique, Paulsen, Carley, Lhotel, Elsa, Gorski, Alexander, Waluk, Jacek, Amabilino, David B., and Veciana, Jaume
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MANGANESE , *METAL ions - Abstract
There is presently a widespread search for materials which present magnetic ordering and appropriate chiroptical properties which would allow the observation of magneto-chiral effects. In this paper, we reflect on the possible uses of organic materials to probe this phenomenon, either as pure compounds or as their coordination compounds with metal ions. [Copyright &y& Elsevier]
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- 2003
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18. Synthesis and characterization of a new chiral nanomagnet
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Domingo, Neus, Gerbier, Philippe, Gómez, Jordi, Ruiz-Molina, Daniel, Amabilino, David B., Tejada, Javier, and Veciana, Jaume
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MANGANESE , *CHIRALITY - Abstract
The dodecanuclear complexes formed between manganese ions and carboxylate anionic ligands are the single molecule magnets (SMMs) with greatest synthetic accessibility and richness of magnetic properties. In this work, we describe a recently synthesized chiral SMM which presents both spontaneous magnetization and optical activity. This objective has been targeted because of the possibility of observing new phenomena related with the synergy between structural chirality, optical activity, and magnetic ordering. [Copyright &y& Elsevier]
- Published
- 2003
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19. Self-assembly of functional chromophores into chiral nanomaterials
- Author
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Oliveras González, Cristina, Amabilino, David B., Aliaga Alcalde, Núria, Hernando Campos, Jordi, and Universitat Autònoma de Barcelona. Departament de Química
- Subjects
Porphyrins ,Auto-assemblatge ,Ciències Experimentals ,Auto-emsamblaje ,Quiralitat ,Quiralidad ,Porfirines ,Self-assembly ,Chirality ,Porfirinas - Abstract
Aquesta tesi es basa en l’estudi de l’auto-assemblatge de porfirines quirals i la utilització d’aquests cromòfors en l’organització de molècules orgàniques de manera quiral. Les porfirines i els seus derivats son colorants – uns d’ells naturals - formats per quatre anells pirròlics units entre si per un enllaç metilè i les quals formen part d’una família de cromòfors cíclics. Les porfirines estan presents a la natura i juguen un paper important in diferents processos en sistemes biològics, especialment aquells de transport d’electrons or com a captadors de llum. És important remarcar que tots aquests macrocicles posseeixen un ambient quiralt provinent de l’auto-assemblatge a traves de d’enllaços no-covalents tal com ponts d’hidrogen, interaccions febles de van der Waals, interaccions π-π i enllaços de coordinació mitjançant un centre metàl·lic. L’estudi de l’auto-assemblatge de porfirines i metal·loporfirines ha rebut un gran interès els darrers anys degut a les propietats òptiques, elèctriques i magnètiques que aquests cromòfors presenten. És per aquest motiu, que aquests pigments naturals puguin ser utilitzats en múltiples aplicacions en camps de la nanoelectrònica, celes fotovoltaiques o com a transistors d’efecte de camp orgànic (OFETs). Les porfirines i metal·loporfirines estudiades en aquest treball contenen en la seva estructura diferents grups capaços de dirigir l’auto-assemblatge. A més a més, la presència de de l’ió zinc (II) enllaçat a l’interior de l’anell porfirínic pot també influir en l’organització de l’agregat, ja que el zinc presenta una gran tendència a coordinar-se amb lligants axials que continguin àtoms d’oxigen, sofre o nitrogen en la seva estructura. És important destacar, l’important rol del grup quiral en els substituents de l’anell de porfirina, ja que el nombre i posició dels centres esterogènics afecten directament en la transferència de quiralitat des de nivell molecular al sistema supramolecular. Tenint totes aquestes consideracions en ment, el disseny d’estructures supramolecular quirals basades en porfirines ha estat dut a terme per tal de determinar la influència de la quiralitat en la morfologia dels agregats i per tant la influencia de l’organització quiral de les estructures supramoleculars en l’eficiència del transport de càrrega per a futures aplicacions. S’ha pogut observar en els estudis d’auto-assemblatge d’una família de metal·loporfirnes amb grups amida quirals i grups piridina en dissolució i en estat sòlit la influència del nombre i posició dels diferents grups en l’activitat òptica dels agregats i en la seva morfologia. S’ha determinat que els agregats s’han format mitjançant la coordinació d’un grup piridina amb el zinc (II) metàl·lic. S’ha estudiat l’auto-assemblatge d’una molècula simètrica C3 basada en porfirines quirals en diferents dissolvents de diferents polaritats i la morfologia dels agregats formats quan aquests son dipositats sobre una superfície de grafit o mica. Finalment, l’organització supramolecular d’un complex format per una metal·loporfirna quiral i un bloc copolímer s’ha estudiat en dissolució, observant-se mitjançant CD una transferència de la quiralitat des de la porfirina lliure al complex., This thesis focuses on the self-assembly studies of chiral porphyrins and the use of these chromophores to drive the organization optically active molecular materials. Porphyrins and their derivatives are pigments – some found in natural systems - that are made up of four pyrrolic units linked by methine bridges and they form part of an important class of cyclic chromophores. Porphyrins are present in nature developing important processes in biological systems, especially in electron transport or light harvesting systems. It is important to emphasize that these macrocycles have chiral environment arising from self-organization through non-covalent interactions such as hydrogen-bonding, van der Waals interactions, π-π interactions and metal coordination. The study of the self-assembly of porphyrins and metalloporphyrins has received great attention in recent years because of their optical, electronic and magnetic properties that make these chromophores suitable for a broad range of potential applications such as nanoelectronic devices, solar cells or organic field-effect transistors (OFETs). The porphyrins and metalloporphyrins studied in this work contain in their structures different moieties capable to direct the self-assembly. Moreover, the presence of a zinc (II) metal ion in the core of the chromophoric ring can influence in their organization due to its ability to coordinate with oxygen, nitrogen and sulfur containing derivatives. The important role of the chiral group in the periphery of the porphyrin ring is noteworthy. Therefore, the number and position of the stereogenic centers directly affect the chiral transfer from molecular level to supramolecular systems. Bearing these considerations in mind, the design of chiral supramolecular systems based on porphyrins has been carried out in order to determine the influence of chirality in the hierarchy morphology of the aggregates and in consequence the influence of the chiral organization in the efficiency for further applications. The self-assembly studies in solution and in the solid state of a family of metalloporphyrins which contain in their structure chiral amide groups and pyridyl groups show the influence in the constitution in their optical activity and morphology of the aggregates, all of them formed as a main interaction the coordination between the pyridyl unit with the zinc (II) metal ion. The self-assembly of a C3 symmetric molecule based on chiral porphyrins has been studied by CD in different solvents and the morphology of the aggregates by AFM after be deposited on HOPG and mica. Finally, the supramolecular organization of a chiral metalloporphyrin-block copolymer complex has been studied in solution. Moreover, the CD studies suggested chirality transfer from chiral metalloporphyrin to the superstructure of the complex.
- Published
- 2015
20. Transfer of chirality from amphiphiles into materials
- Author
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Jakub Saletra, Wojciech, Amabilino, David B., and Universitat Autònoma de Barcelona. Departament de Química
- Subjects
Ciències Experimentals ,STM ,Chirality ,Self-assembly monoleguer - Abstract
En esta tesis ha estudiado la influencia de la geometría de las moléculas en las monocapas de autoensamblaje (SAM) de ácidos quirales, se ha presentado la síntesis de la familia de anfifílicos quirales. Cada compuesto se ha medido con STM en la interfaz grafito-1-phenyloctanano como un único enantiómero y como una mezcla racémica para comprobar la transferencia de quiralidad de molécula a SAM a dos dimensiones. Se ha encontrado que las moléculas con geometría curvada - 1,3Ph y 2,7Naph, forman dominios muy regulares en el caso de enantiómero puro y conglomerado en el caso de la mezcla racémica. Los otros compuestos forman diversos polimorfos (hasta cuatro en el caso de 1,5Naph) o cristales 2D irregulares (2,6Naph), y cuando se ha estudiado la mezcla racémica, se han encontrado las SAM desordenadas o un pseudoracemato para 4,4'Biph. Las mezclas de los derivados de naftaleno se han estudiado en la interfaz grafito-1-phenyloctano para comprobar si los compuestos son capaces de formar monocapas mixtas, por otra parte las mismas mezclas se han medido con calorimetría de barrido diferencial (DSC) y difracción de rayos X (DRX) para comparar el comportamiento en los sistemas de dos y tres dimensiones. Se ha descubierto que los ácidos forman monocapas mixtas estables, y en un caso se ha observado un comportamiento de solución sólida. El reconocimiento quiral entre los ácidos anfifílicos se ha comprobado con un amina quiral modelo trans-1,2-diaminociclohexano (DACH) - para descubrir que, en caso del ácido 1,3Ph y 2,7Naph, hay un reconocimiento quiral y la formación diastereoselectiva de un complejo en la interfaz de grafito-1-phenyloctane. En el caso del ácido 2,7Naph and DACH también se ha observado la formación de multicapas. Se ha utilizado el modelado molecular para obtener mejor idea de las fuerzas y el ensamblaje de las moléculas. El ácido 1,3Ph fue elegido para estudiar su capacidad de reconocimento con diversas aminas quirales y aquirales incluyendo compuestos utilizados como medicamentos: Metoprolol, Antenolol y Verpamil. Se ha encontrado, en el caso de Metoprolol que hay una complejación preferencial de uno de los enantiómeros en la interfaz grafito-1-phenyloctano. Se han usado mezclas de ácidos para comprobar su capacidad para actuar como un agente de resolución en dos sistemas dimensionales, pero no se ha encontrado una evidencia clara de mejoras con respecto a los enatiomeros puros, debido a la adsorción competitiva. Además se ha llevado a cabo la serie de experimentos de mezclas en masa de ácido 1,3Ph y DACH para comprobar si había un reconocimiento quiral en sistemas tres dimensionales. Las muestras se han comprobado con DSC, XRD y en microscopio óptico polarizado (POM) en un rango de temperaturas para descubrir el comportamiento de fase y el ensamblaje de las moléculas. La quiralidad del compuesto juega un papel determinante en el comportamiento de fase de los materiales., In this thesis study of influence of geometry of the molecules on self-assembly monolayers (SAM) of chiral acids was studied, the synthesis of family of chiral amphiphiles was presented. Each compound was measured with STM at the graphite-1-phenyloctane interface as a single enatiomer and as a racemic mixture to check the transfer of chirality from molecule to two dimensional SAM. It was found that the bent-core molecules – 1,3Ph and 2,7Naph form very regular domains in the case of pure enatiomer and conglomerate in the case of racemic mixture. The other compounds form various polymorphs (up to four in the case of 1,5Naph) or irregular 2D crystals (2,6Naph), and when the racemic mixture was studied, the SAM was disordered or a pseudoracemate was found for 4,4´Biph. The mixtures of the naphthalene derivatives were studied at the graphite-1-phenyloctane interface to check if compounds are capable of forming mixed monolayers, moreover the same mixtures were measured with differential scanning calorimetry (DSC) and X-ray diffraction (XRD) to compare behaviour in two and three dimensional systems. It was discovered that the acids form stable mixed monolayers, and in one case a solid solution behaviour was observed. The chiral recognition between amphiphilic acids was checked with a model chiral amine -1,2 trans-diaminocyclohexane (DACH) - to discover that in case of acid 1,3Ph and 2,7Naph there is a chiral recognition and diastereselective formation of a complex at the graphite-1-phenyloctane interface. In the case of acid 2,7Naph and DACH also formation of multilayers was observed. The molecular modelling was used to get insight into the forces and packing of the molecules. The acid 1,3Ph was chosen to study its capability of binding various chiral and achiral amines including compounds used as medicaments: Metoprolol, Antenolol and Verpamil. It was found in the case of Metoprolol that there is preferential binding of one of the enantiomers at the graphite-1-phenyloctane interface. Also mixtures of acids was checked for their capability to act as a resolving agent in two dimensional systems, but no clear evidence of improvements over the pure were observed because of competitive adsorption. Also the series of experiments of bulk mixtures of acid 1,3Ph and DACH was performed to check if there is a chiral recognition in three dimensional systems. The samples were checked with DSC, XRD and in polarized optical microscope (POM) in a range of temperatures to discover the phase behaviour and packing of molecules. The chirality of the component plays a determining role in the phase behaviour of the materials.
- Published
- 2013
21. Amino Acid Based Metal-Organic Nanofibers.
- Author
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lmaz, Inhar, Rubio-Martínez, Marta, SaIetra, Wojciech J., Amabilino, David B., and Maspoch, Daniel
- Subjects
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NANOFIBERS , *COORDINATION polymers , *ASPARTIC acid , *METAL ions , *CHIRALITY , *POLYMERIZATION , *CIRCULAR dichroism , *COPPER isotopes - Abstract
The article focuses on the production of chiral coordination polymer nanofibers with the use of aqueous/organic interfacial coordinated polymerization. It mentions the use of Circular Dichroism (CD) spectroscopy to study the chirality of Cu-Asp fibers formed from aspartic (Asp) acids and copper (Cu) metal ions. Results of the experiments show that long chiral nanofibers can be produced with the use of traditional coordination chemistry and biologically obtained elements.
- Published
- 2009
- Full Text
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