Search results for "Pram"

The Effect of the Side Chain on Gelation Properties of Bile Acid Alkyl Amides

2021

Abstract Six bile acid alkyl amide derivatives were studied with respect to their gelation properties. The derivatives were composed of three different bile acids with hexyl or cyclohexyl side chains. The gelation behaviour of all six compounds were studied for 36 solvents with varying polarities. Gelation was observed mainly in aromatic solvents, which is characteristic for bile‐acid‐based low molecular weight gelators. Out of 108 bile acid‐solvent combinations, a total of 44 gel systems were formed, 28 of which from lithocholic acid derivatives, only two from deoxycholic acid derivatives, and 14 from cholic acid derivatives. The majority of the gel systems were formed from bile acids with…

Diversity at the nanoscale : laser-oxidation of single-layer graphene affects Fmoc-phenylalanine surface-mediated self-assembly

2023

We report the effects of a laser-oxidized single layer graphene (SLG) surface on the self-assembly of amphiphilic gelator N-fluorenylmethoxycarbonyl-L-phenylalanine (Fmoc-Phe) towards an gel–SLG interface. Laser oxidation modulates the levels of hydrophobicity/hydrophilicity on the SLG surface. Atomic force, scanning electron, helium ion and scattering scanning nearfield optical microscopies (AFM, SEM, HIM, s-SNOM) were employed to assess the effects of surface properties on the secondary and tertiary organization of the formed Fmoc-Phe fibres at the SLG–gel interface. S-SNOM shows sheet-like secondary structures on both hydrophobic/hydrophilic areas of SLG and helical or disordered structu…

Rapid Self-Healing and Thixotropic Organogelation of Amphiphilic Oleanolic Acid–Spermine Conjugates

2021

Natural and abundant plant triterpenoids are attractive starting materials for the synthesis of conformationally rigid and chiral building blocks for functional soft materials. Here, we report the rational design of three oleanolic acid–triazole–spermine conjugates, containing either one or two spermine units in the target molecules, using the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction. The resulting amphiphile-like molecules 2 and 3, bearing just one spermine unit in the respective molecules, self-assemble into highly entangled fibrous networks leading to gelation at a concentration as low as 0.5% in alcoholic solvents. Using step-strain rheological measurements, we show ra…

Kemiallisten ja fysikaalisten ärsykkeiden vaikutus supramolekulaaristen geelien muodostumiseen ja geelin rakenteeseen

2016

Tutkielman kirjallisessa osassa perehdyttiin siihen, kuinka kemialliset ja fysikaaliset tekijät vaikuttavat geelin muodostukseen ja siihen, kuinka näillä ärsykkeillä voidaan vaikuttaa geelin rakenteeseen, ominaisuuksiin tai olomuotoon. Kokeellisessa osassa tutkittiin kuinka jäähtymisprofiilin vaikutusta geelinmuodostuksen nopeuteen ja geelin rakenteeseen. Kokeissa käytettiin gelaattorina koolihapon ja L-metioniinimetyyliesterin amidia, joka liuotettiin ultraäänikäsittelyn ja lämmityksen avulla eri liuottimiin, jotka olivat o-ksyleeni, tolueeni, bentseeni ja tert-butyylibentseeni. Pääasiallisena tutkinnan kohteina olivat tolueenin, bentseenin ja tert-butyylibentseenin ja gelaattorin muodosta…

IONOGEL IBRIDI: SISTEMI ADSORBENTI PER LA RIMOZIONE DI COMPOSTI FARMACEUTICI DALLE ACQUE INQUINATE

Supramolecular Hydro- and Ionogels: A Study of Their Properties and Antibacterial Activity.

2017

Diimidazolium-based organic salts, bearing peptides or amino acids as anions have been synthesised and tested for their gelling ability in biocompatible solvents. These low molecular weight salts were successfully used as gelators in phosphate buffered saline (PBS) solution and ionic liquids. Then, the properties of the obtained soft materials were analysed in terms of melting temperature and gel strength as accounted for by rheological investigations. The gel-phase formation was studied by using UV/Vis and resonance light scattering measurements, whereas the morphology of the soft materials was analysed by using polarised optical microscopy and scanning electron microscopy. To get informat…

Communication between iron(II) building blocks in cooperative spin transition phenomena

2003

[EN] In the present article we discuss the cooperative nature of the spin crossover phenomenon in iron(II) complexes, providing a perspective of the state of the art in this area. The first aspect we discuss is the role of the intermolecular interactions, more precisely the ¿-interactions, in mononuclear complexes. We show that by playing with the nature of the ligands, aliphatic, aromatic, or extended aromatic, it is possible to create stronger cohesive forces and receive a more cooperative response from the compound. In the next step the singular family of bipyrimidine-bridged iron(II) dinuclear compounds is presented as the simplest example of polynuclear spin crossover complexes exhibit…

A coumarin based gold(I)-alkynyl complex: a new class of supramolecular hydrogelators

2015

A phosphine-gold(I)-alkynyl-coumarin complex, [Au{7-(prop-2-ine-1-yloxy)-1-benzopyran-2-one}- (DAPTA)] (1), was synthesized and the formation of long luminescent fibers in solution was characterized via fluorescence microscopy and dynamic light scattering. The fibers presented strong blue and green luminescence, suggesting that the gold(I) in the complex increased intersystem crossing due to the heavy atom effect, resulting in a significant increase in triplet emission. The X-ray structure of the fibers indicates that both aurophilic, π–π interactions and hydrogen bonding contribute to their formation in aqueous solvents. peerReviewed

Supramolecular Catalytic Gels [Elsevier Award]

Mācīšanās no vienaudžiem kā viena no iespējām lasītprasmes apguvē 5-6 gadu veciem bērniem pirmsskolā

2022

Darba tēma: Mācīšanās no vienaudžiem kā viena no iespējām lasītprasmes apguvē 5-6 gadu veciem bērniem pirmsskolā Darba autore: Rasa Celitāne Darba zinātniskā vadītāja: profesore, Dr. pead. Baiba Kaļķe Darba apjoms: 78 lpp. , 5 pielikumi, izmantots 60 literatūras avots Atslēgvārdi: LASĪTPRASME, VIENAUDŽI, 5-6 GADUS VECI BĒRNI. Pētījuma mērķis: izzināt, kā vienaudži var palīdzēt apgūt lasītprasmi 5-6 gadus veciem bērniem pirmsskolā. Pētījuma mērķis ir analizēt un pētīt kā vienaudži palīdz apgūt lasītprasmi.Izvirzītā mērķa sasniegšanai tika analizēta un pētīta teorētiskā literatūra par lasītprasmi un nosacījumiem tās apguvē. Papildus tika pētītas arī 5-6 gadus vecu bērnu psiholoģiskās un fizio…