scholarly journals Tuning Gel State Properties of Supramolecular Gels by Functional Group Modification

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3472 ◽  
Author(s):  
Dipankar Ghosh ◽  
Matthew T. Mulvee ◽  
Krishna K. Damodaran
Keyword(s):  
Self Assembly ◽  
Thermal Stabilities ◽  
Factors Affecting ◽  
Sem Image ◽  
Group Modification ◽  
Fibrous Morphology ◽  
Low Molecular Weight Gelators ◽  
Functional Group Modification ◽  
Gel Network ◽  
Weak Gels

The factors affecting the self-assembly process in low molecular weight gelators (LMWGs) were investigated by tuning the gelation properties of a well-known gelator N-(4-pyridyl)isonicotinamide (4PINA). The N―H∙∙∙N interactions responsible for gel formation in 4PINA were disrupted by altering the functional groups of 4PINA, which was achieved by modifying pyridyl moieties of the gelator to pyridyl N-oxides. We synthesized two mono-N-oxides (INO and PNO) and a di-N-oxide (diNO) and the gelation studies revealed selective gelation of diNO in water, but the two mono-N-oxides formed crystals. The mechanical strength and thermal stabilities of the gelators were evaluated by rheology and transition temperature (Tgel) experiments, respectively, and the analysis of the gel strength indicated that diNO formed weak gels compared to 4PINA. The SEM image of diNO xerogels showed fibrous microcrystalline networks compared to the efficient fibrous morphology in 4PINA. Single-crystal X-ray analysis of diNO gelator revealed that a hydrogen-bonded dimer interacts with adjacent dimers via C―H∙∙∙O interactions. The non-gelator with similar dimers interacted via C―H∙∙∙N interaction, which indicates the importance of specific non-bonding interactions in the formation of the gel network. The solvated forms of mono-N-oxides support the fact that these compounds prefer crystalline state rather than gelation due to the increased hydrophilic interactions. The reduced gelation ability (minimum gel concentration (MGC)) and thermal strength of diNO may be attributed to the weak intermolecular C―H∙∙∙O interaction compared to the strong and unidirectional N―H∙∙∙N interactions in 4PINA.

scholarly journals Role of N–Oxide Moieties in Tuning Supramolecular Gel-State Properties

Gels ◽  
2020 ◽  
Vol 6 (4) ◽  
pp. 41
Author(s):  
Dipankar Ghosh ◽  
Ragnar Bjornsson ◽  
Krishna K. Damodaran
Keyword(s):  
Functional Groups ◽  
Self Assembly ◽  
Network Formation ◽  
Spatial Arrangement ◽  
Sem Images ◽  
Thermal Stabilities ◽  
Supramolecular Gel ◽  
Low Molecular Weight Gelators ◽  
Gel Network

The role of specific interactions in the self-assembly process of low molecular weight gelators (LMWGs) was studied by altering the nonbonding interactions responsible for gel formation via structural modification of the gelator/nongelator. This was achieved by modifying pyridyl moieties of bis(pyridyl) urea-based hydrogelator (4–BPU) and the isomer (3–BPU) to pyridyl N–oxide compounds (L1 and L2, respectively). The modification of the functional groups resulted in the tuning of the gelation properties of the parent gelator, which induced/enhanced the gelation properties. The modified compounds displayed better mechanical and thermal stabilities and the introduction of the N–oxide moieties had a prominent effect on the morphologies of the gel network, which was evident from the scanning electron microscopy (SEM) images. The effect of various interactions due to the introduction of N–oxide moieties in the gel network formation was analyzed by comparing the solid-state interactions of the compounds using single crystal X-ray diffraction and computational studies, which were correlated with the enhanced gelation properties. This study shows the importance of specific nonbonding interactions and the spatial arrangement of the functional groups in the supramolecular gel network formation.

Factors Affecting Molecular Self-Assembly and Its Mechanism

2012 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Hueyling Tan
Keyword(s):  
Self Assembly ◽  
Building Blocks ◽  
Molecular Engineering ◽  
Molecular Structures ◽  
Polymer Science ◽  
New Approach ◽  
Factors Affecting ◽  
Dna Structures ◽  
Self Assembling ◽  
Wide Range

Molecular self-assembly is ubiquitous in nature and has emerged as a new approach to produce new materials in chemistry, engineering, nanotechnology, polymer science and materials. Molecular self-assembly has been attracting increasing interest from the scientific community in recent years due to its importance in understanding biology and a variety of diseases at the molecular level. In the last few years, considerable advances have been made in the use ofpeptides as building blocks to produce biological materials for wide range of applications, including fabricating novel supra-molecular structures and scaffolding for tissue repair. The study ofbiological self-assembly systems represents a significant advancement in molecular engineering and is a rapidly growing scientific and engineering field that crosses the boundaries ofexisting disciplines. Many self-assembling systems are rangefrom bi- andtri-block copolymers to DNA structures as well as simple and complex proteins andpeptides. The ultimate goal is to harness molecular self-assembly such that design andcontrol ofbottom-up processes is achieved thereby enabling exploitation of structures developed at the meso- and macro-scopic scale for the purposes oflife and non-life science applications. Such aspirations can be achievedthrough understanding thefundamental principles behind the selforganisation and self-synthesis processes exhibited by biological systems.

scholarly journals Astral hydrogels mimic tissue mechanics by aster-aster interpenetration

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qingqiao Xie ◽  
Yuandi Zhuang ◽  
Gaojun Ye ◽  
Tiankuo Wang ◽  
Yi Cao ◽  
...  
Keyword(s):  
Common Core ◽  
Self Assembly ◽  
Master Curve ◽  
Soft Tissues ◽  
Tissue Mechanics ◽  
Fresh Perspective ◽  
Single Master Curve ◽  
Unique Mechanism ◽  
Gel Network

AbstractMany soft tissues are compression-stiffening and extension-softening in response to axial strains, but common hydrogels are either inert (for ideal chains) or tissue-opposite (for semiflexible polymers). Herein, we report a class of astral hydrogels that are structurally distinct from tissues but mechanically tissue-like. Specifically, hierarchical self-assembly of amphiphilic gemini molecules produces radial asters with a common core and divergently growing, semiflexible ribbons; adjacent asters moderately interpenetrate each other via interlacement of their peripheral ribbons to form a gel network. Resembling tissues, the astral gels stiffen in compression and soften in extension with all the experimental data across different gel compositions collapsing onto a single master curve. We put forward a minimal model to reproduce the master curve quantitatively, underlying the determinant role of aster-aster interpenetration. Compression significantly expands the interpenetration region, during which the number of effective crosslinks is increased and the network strengthened, while extension does the opposite. Looking forward, we expect this unique mechanism of interpenetration to provide a fresh perspective for designing and constructing mechanically tissue-like materials.

scholarly journals Chirality, Gelation Ability and Crystal Structure: Together or Apart? Alkyl Phenyl Ethers of Glycerol as Simple LMWGs

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 732
Author(s):  
Alexander A. Bredikhin ◽  
Aidar T. Gubaidullin ◽  
Zemfira A. Bredikhina ◽  
Robert R. Fayzullin ◽  
Olga A. Lodochnikova
Keyword(s):  
Self Assembly ◽  
Chiral Recognition ◽  
Soft Materials ◽  
Gelling Agent ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Types ◽  
Low Molecular Weight Gelators ◽  
Phenyl Ethers

Chiral recognition plays an important role in the self-assembly of soft materials, in particular supramolecular organogels formed by low molecular weight gelators (LMWGs). Out of 14 pairs of the studied racemic and enantiopure samples of alkyl-substituted phenyl ethers of glycerol, only eight enantiopure diols form the stable gels in nonane. The formation of gels from solutions was studied by polarimetry, and their degradation with the formation of xerogels was studied by the PXRD method. The revealed crystalline characteristics of all studied xerogels corresponded to those for crystalline samples of the parent gelators. In addition to those previously investigated, crystalline samples of enantiopure para-n-alkylphenyl glycerol ethers [alkyl = pentyl (5), hexyl (6), heptyl (7), octyl (8), nonyl (9)] and racemic 3-(3,5-dimethylphenoxy)propane-1,2-diol (rac-14) have been examined by single crystal X-ray diffraction analysis. Among 22 samples of compounds 1-14 studied by SC-XRD, seven different types of supramolecular motifs are identified, of which only two are realized in crystals of supramolecular gelators. An attempt was made to relate the ability to gel formation with the characteristics of the supramolecular motif of a potential gelling agent, and the frequency of formation of the motif, required for gelation, with the chiral characteristics of the sample.

Access to Metastable Gel States Using Seeded Self‐Assembly of Low‐Molecular‐Weight Gelators

2019 ◽  
Vol 58 (12) ◽  
pp. 3800-3803 ◽  
Author(s):  
Yiming Wang ◽  
Robin M. de Kruijff ◽  
Matija Lovrak ◽  
Xuhong Guo ◽  
Rienk Eelkema ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Self Assembly ◽  
Low Molecular Weight ◽  
Low Molecular Weight Gelators

scholarly journals Thermally tunable selective formation of self-assembled fibers into two orthogonal directions in oriented liquid-crystalline smectic templates

2020 ◽  
Vol 56 (69) ◽  
pp. 9954-9957
Author(s):  
Daisuke Yamaguchi ◽  
Yuka Ikemoto ◽  
Takashi Kato
Keyword(s):  
Molecular Weight ◽  
Self Assembly ◽  
Liquid Crystalline ◽  
Layered Structures ◽  
Low Molecular Weight ◽  
Smectic A ◽  
Orthogonal Grid ◽  
Self Assembled ◽  
Low Molecular Weight Gelators ◽  
Selective Formation

Two orthogonal (grid-like) and one directional fibrous structures are selectively formed through anisotropic self-assembly of low-molecular-weight gelators in liquid-crystalline smectic A templates depending on thermally tuned layered structures.

scholarly journals Preparation of Citric Acid Crosslinked Chitosan/Poly(Vinyl Alcohol) Blend Membranes for Creatinine Transport

2018 ◽  
Vol 16 (2) ◽  
pp. 144 ◽  
Author(s):  
Retno Ariadi Lusiana ◽  
Dwi Siswanta ◽  
Mudasir Mudasir
Keyword(s):  
Citric Acid ◽  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Crosslinking Reaction ◽  
Transport Capacity ◽  
Chitosan Membrane ◽  
Group Modification ◽  
Crosslinked Chitosan ◽  
Pass Through ◽  
Functional Group Modification

Preparation of membrane using crosslinking reaction between chitosan and citric acid showed that functional group modification increased the number of active carrier groups which lead to better transport capacity of the membrane. In addition, the substitution of the carboxyl group increased creatinine permeation of chitosan membrane. The transport capacity of citric acid crosslinked chitosan membrane for creatinine was found to be 6.3 mg/L. The presence of cyanocobalamin slightly hindered the transport of creatinine although compounds did not able to pass through citric acid crosslinked chitosan/poly(vinyl alcohol) blend membrane, as compounds no found in the acceptor phase.

Sign in / Sign up

Export Citation Format

Share Document