Effects of Main-chain and Chain-ends on the Organogelation of Stearoyl Appended Pendant Valine Based Polymers

In this work, we investigated the effect of hydrophobic interactions between the polymeric backbone and chain-end groups on the self-assembly pathway of stearoyl appended side-chain valine（Val）-based poly（methacrylate/acrylate） homopolymers in different organic hydrocarbons. Gelation studies conducted revealed that while polymers with polyacrylate as backbone induces gelation in several organic hydrocarbons, polymers with polymethacrylate in the main-chain significantly hinders macroscopic gelation. Morphology of the organogels was analysed by field emission scanning electron microscopy（FESEM）, and mechanical strengths of the organogels were determined by rheological measurements. Reversible addition-fragmentation chain transfer（RAFT） polymerization chain transfer agents（CTA）s, [R1―S―C=（S）―S―R2] with different ―R1 and ―R2 groups, have been employed to study the effect of structural variation at the chain-end on macroscopic assembly mechanism. We found that the additional interactions between terminal groups via hydrogenbonding or π-π stacking interactions or both help to build up the self-assembly pathway and thereby produces mechanically stable organogels.

Novel four-hydrogen-bond assembled oligoamide dimer with pyrazoline moieties and its photoluminescent properties

In this paper, the synthesis and characterization of a triarylpyrazoline modified four-H-bonded molecular duplex are described. Its molecular structure has been confirmed by ^1H NMR and ESI-MS. The duplex emits strong pure blue light peaking at 448 and 452 nm under UV photoexcitation in solution and solid state, respectively, and its relative photoluminescence quantum efficiency in solution is determined as 0.778 using quinine sulfate as reference. In concentration of 〉40 mmol/L, the duplex can gelate DMSO, and the organogel formed shows good pure blue photoluminescence too. This novel duplex, for its well-defined structure and efficient photoluminescence property, is a prospective candidate for pure blue electroluminescent emitter.

Phase-Selective Gelators Based on p-Alkoxybenzoyl for Oil Spill Recovery and Dye Removal

Oil spills result in tremendous damage to the environment and ecosystem.In this study,several p-alkoxybenzoyl-based gelators(1,2a,2b,2c,3)synthesized from commercially available materials were designed for recovering oil from an oil–water mixture.Gels with remarkable gelation ability in various oils were characterized by nuclear magnetic resonance,Fourier transform infrared spectroscopy and X-ray diffraction to study the driving forces of self-assembly.Notably,these gelators could achieve the goal of recycling oil from the oil–water mixture at room temperature.In addition,gelator 2b could be used to remove toxic dyes from aqueous solutions with high efficiency.Therefore,these compounds were considered promising materials for oil spill recovery and dye removal due to their practicality and high efficiency.

Organogels, hydrogels and bigels as transdermal delivery systems for diltiazem hydrochloride

In the present study,gel formulations of organogels,hydrogels,and oleo-hydrogel(bigels)were evaluated as transdermal drug delivery systems for diltiazem HCL(DH).Organogels were prepared using soya-bean oil(SO)as a solvent and span 60(Sp 60),cetyl alcohol(CA)or lecithinpluronic(PLO)as organogelators without and with different surfactants(2%w/w)namely span 80(Sp80),tween 20(T20)and tween 80(T80).On the other hand,hydrogels were formulated using Hydroxypropyl-methylcellulose(HPMC)polymer and bigels were prepared by mixing organogels with HPMC hydrogels.The prepared gels were analyzed microscopically,thermally by DTA and for pH,and viscosity.The effect of gelator used,surfactant types and pH of the sink on DH release from cellophane membrane was investigated.In addition,the DH permeability across the rabbit skin was evaluated.Finally,the in vivo performance of various gel formulationswas assessed based on the hypotensive effects of the drug using hypertensive albino male rat models.The microscopical analysis indicated that the solid fibers formed by gelator particles form the backbone of the organogels while bigels appeared as emulsion like.The addition of surfactants showed an increase in organogel viscosity.The thermal analysis of organogels indicated that the drug present in amorphous not in crystalline form.The release studies indicated that DH release from organogels,hydrogels and bigels could be controlled.The included surfactants decreased the DH release and permeation from organogels compared to those without surfactants using either Sp60 or CA.HPMC hydrogel and Bigels showed higher DH release and permeation rates when compared to organogels.The percent DH released in different pH values was in the following descending order:pH5.5>pH1.2>pH6.8>pH7.4.The in vivo antihypertensive activity of DH using different transdermal gels is arranged as following:hydrogels>PLO organogel>bigel>Sp 60 organogel.

Synthesis and Self-assembling of Coumarin-based Low-molecular Weight Organogelators

Four coumarin derivatives（4a-4d） with different alkoxy chains were synthesized. It was found that compound 4d showed a better gelation ability than the other compounds, for example, it could self-assemble into organogels in various organic fluids via ultrasound treatment or heating-cooling process, whereas compound 4c could only gel in a few mixed solvents and compounds 4a, 4b could not form organogel. The results from fluorescent and FT-IR spectra indicate that π-π interaction had an effect on the formation of the organogels of compound 4d besides H-bonding and van der Waals interaction, which were the driving forces for the self-assembling of compound 4c in gel state. The gel of compound 4d in toluene could emit strong fluorescence under UV irradiation and the [2＋2] cyclo-addition was suggested by ^1H NMR and fluorescence spectroscopy. This light-sensitive organogel might find application in optical materials.

Comparison of Chromatographic Performance for L-Phenylalanine-Derived Organic Phases on Silica by “Grafting from” and “Grafting to” Strategies

L-phenylalanine-derived polymerizable organogel, N’-octadecyl-Nα-(4-vinyl)-benzoyl-L-phenylalanineami- de (4) has been prepared according to the procedure described elsewhere. Compound 4 was successfully polymerized by surface initiated atom transfer radical polymerization (ATRP) from the initiator grafted silica particles (sil-poly4). It was also telomerized with 3-mercaptopropyltrimethoxysilane (MPS) and the telomer (T4) was grafted on to silica (sil-T4). TGA and elemental analysis measurement revealed that higher amount of polymer can graft by ATRP process than that of “grafting to” strategy. The results of 13C CP/MAS NMR measurement showed that the N-alkyl chain of the grafted polymers for both sil-poly4 and sil-T4 remained as less ordered gauche conformational form on silica surface and no inversion to trans form was occurred until temperature is increased up to 50?C. The retention of alkylbenzene samples showed that sil-poly4 prepared by “grafting from” method yielded extremely higher retention than conventional C18 phase however, sil-T4 prepared by conventional “grafting to” method showed lower retention than C18 phase. Aspects of molecular recognition were evaluated by the retention studies of a series of polycyclic aromatic hydrocarbons (PAHs) and aromatic positional isomers. We have observed sil-T4 yielded slightly higher selectivity for PAHs than sil-poly4 regardless the fact that it has low surface coverage and lower hydrophobic interactions. The enhanced selectivity observed for sil-T4 than C18 phases and sil-poly4 can be explained by the π - π interactions between the guest PAHs and carbonyl groups present in the polymer chain. In addition the aromatic moieties of compound 4 that aggregates through π - π interactions also contribute to the separation of PAHs for both sil-poly4 and sil-T4. The minimal π - π interactions between the carbonyl groups and guest molecules for sil-poly4 probably due to the presence of long chain initiator which restrict the polymer to form order thin layer over silica surface.

Fluoride-Responsive Organogel Based on Hydrazide Derivatives

An organogelator named N-[3-(hydroxy)-4-(dodecyloxy)-benzoyl]-N’ (4’-nitro-benzoyl) hydrazide (D12) was synthesized. It could form stable gels in some of the tested organic solvent. SEM images revealed that the molecules self- assembled into fibrous aggregates in the xerogels. The X-ray diffraction analysis showed that the xerogel exhibited a layered structure. FT-IR studies confirmed that intermolecular hydrogen bonding between C=O and N-H groups was the major driving force for gelation of organic solvents. The gel exhibited gel-sol transition and color change upon addition of F- . An extended conjugated system formed through the phenyl group and a five-membered ring based on intramolecular hydro-gen bonding between the oxygen atom near the deprotonation nitrogen atom and the other NH, which is responsible for the dramatic color change upon addition of F- .

Versatile Organogels of Aluminum Oxide Subnanosheets for Locking Solvents and Adhesion

Herein,we present a facile strategy to prepare versatile aluminum oxide subnanometer nanosheets with oleic acid and stearic acid ligands(OA-Al SNSs and SA-Al SNSs,respectively).The size effect endows subnanosheets with abundant acting sites,remarkable intermolecular interactions,and unique polymer-like properties,including flexibility,viscoelasticity,and sol-gel transitions,which is quite different from traditional inorganic materials.Consequently,subnanosheets could form freestanding organogels and OA-Al SNSs exhibit satisfying semisolidification of various solvents,making it an intriguing candidate for the safe storage and transportation of solvents.Furthermore,SA-Al SNSs exhibit excellent adhesive properties of high strength on diverse substrates,and it is easy to erase it without any damage,demonstrating the promising prospects in practical applications.

Reconfigurable and orthogonal stiffness-structure patterning of dynamically crosslinked amphigels

Patterning diversified properties and surface structure of polymer materials are of great importance toward their potential in biology,optics,and electronics.However,achieving both the patternability of stiffness and microstructure in a reconfigurable manner remains challenging.Here,we prepare amphigels crosslinked by dynamic disulfide bonds,which can be reversibly swollen by immiscible water or liquid paraffin.In the paraffingel form,the materials exhibited a high modulus of 130 MPa due to densified hydrogen bonds.Whereas swollen by water,the modulus fell over two orders of magnitude owing to the destruction of the hydrogen bonds.Via regionalized swelling of the solvents,well-controlled and rewritable soft/stiff mechanical patterns can be created.On the other hand,the dynamic exchange of the disulfide crosslinking enables mechanophoto patterning to fabricate sophisticated macrogeometries and microstructures.The reconfigurable stiffness-structure patterning can be manipulated orthogonally,which will create more application opportunities beyond conventional hydrogels and organogels.

Towards a universal organogelator:A general mixing approach to fabricate various organic compounds into organogels

Low-molecular-weight organogels(LMOG) have been attracting a surge interest in fabricating soft materials.Although the finding of the gelator molecules has been developed from serendipity to objective design,the achievement of the gelator molecules still needs good design and tedious organic synthesis.In this paper,we proposed a simple and general mixing approach to get the organogel for nearly all the organic compounds and even soluble nanoparticles without any modification.We have designed a universal gelator molecule,which forms organogels with more than 40 kinds of organic solvents from aploar to polar solvents.More interestingly,when other organic compounds or even nanomaterials,which are soluble in certain organic solvents,are mixed with this gelator molecule,they can form organogels no matter whether the individual compounds could form organogel or not.This method is applicable to nearly all kinds of soluble organic compounds and opens an efficient and universal way to fabricate gel materials.

Organogelators based on p-alkoxylbenzamide and their self-assembling properties

A series of p-alkoxylbenzamides featuring a long alkyl chain have been synthesized and are readily to form stable gels in a variety of organic solvents. Their selfassembly properties and structure-property relationship were investigated by scanning electron microscopy, X-ray diffraction, IH nuclear magnetic resonance, and Fourier transform infrared spectroscopy. The gels formed were multi-responsive to environmental stimuli such as temperature and fluoride anion. The results show that a combination of hydrogen bonding, n-n stacking and van der Waals interaction result in the aggregation of palkoxylbenzamides to form three-dimension networks, depending on the length of the long alkyl chain.

Preparation of optical active polydiacetylene through gelating and the control of supramolecular chirality

Achiral diacetylene 10,12-pentacosadinoic acid (PCDA) and a chiral low-molecular-weight organogelator could form co-gel in organic solvent and it could be polymerized in the presence of Zn(II) ion or in the corresponding xerogel under UV-irradiation. Optically active polydiacetylene (PDA) were subsequently obtained. Supramolecular chirality of PDA could be controlled by the chirality of gelators. Left-handed and right-handed helical fibers were obtained by using Land D-gelators in xerogels respectively, and CD spectra exhibited mirror-image circular dichroism. The PDA in xerogel exhibited typical blue-to-red transition responsive to the temperature and pH, while the supramolecular chirality of PDA showed a corresponding change.

Bioinspired wet-resistant organogel for highly sensitive mechanical perception

Smart flexible electronics with underwater motion detection have become a promising research aspect in intelligent perception.Inspired by the strong adaptability of marine creatures to complex underwater environments,conventional biocompatible hydrogels are worth developing into organogels with preferred underwater adhesive properties,hydrophobic and antiswelling performance,and motion perception ability.Herein,a highly sensitive organogel sensor exhibiting good hydrophobicity,electromechanical properties,and adhesion properties was prepared for underwater utilization by regulating the chemical components and internal interactions.The synergistic effect of massive reversible noncovalent bonds ensures the organogel’s excellent underwater adhesion to multifarious substrates.Meanwhile,the interactions of hydrophobic conductive fillers and the dynamic hydrophobic associations in the organogel endow it with satisfactory hydrophobic performance(contact angle of111.8°)and antiswelling property(equilibrium swelling ratio of-31%after 15-day immersion).The fabricated flexible organogel strain sensor exhibits high sensitivity(gauge factor of1.96),ultrafast response rate(79.1 ms),low limit of detection(0.45 Pa),and excellent cyclic stability(1044 tensile cycles followed by 3981 compressive cycles).Results demonstrate the proposed organogel’s precise perception of sophisticated human motions in air and underwater,which expands its application scenarios.

Nanomagnetic Organogel Based on Dodecyl Methacrylate for Absorption and Removal of Organic Solvents

A novel nanomagnetic organogel was synthesized by in situ emulsion polymerization-crosslinking method using dodecyl methacrylate(DDMA) and styrene(St) as monomers, divinylbenzene(DVB) as a crosslinking agent, azobisisobutyronitrile(AIBN) as an initiator, and Fe_3O_4 as a nanomagnetic particle. Modification of the network was carried out by inclusion of the multi-walled carbon nanotubes(MWCNT) into the organogel matrix. The structure of the nanocomposite was characterized using FTIR spectroscopy, SEM,TEM, TGA/DTG, VSM, and BET analysis. The effects of various parameters such as the amount of crosslinker, initiator, Fe_3O_4, and reaction time as well as monomer ratio on the oil absorption of the organogel were studied. The synthesized organogel can absorb about35.5, 22.1, 29.86, 14.58, 17.6, 15.3, and 13.7 g·g^(-1) of CHCl_3, toluene, CH_2Cl_2, hexane, crude oil, gasoline, and diesel oil, under the optimized polymerization conditions, respectively. The nanocomposite organogels can be easily separated by a magnetic field after absorption of organic solvents.

Intermolecular hydrogen-bond interaction to promote thermoreversible 2'-deoxyuridine-based AIE-organogels

Fluorescent supramolecular nucleoside-based organogels or hydrogels have attracted increasing attention owing to their tunable stability,drug delivery,tissue engineering,and inherent biocompatibility for applications in designing sensors.As the temperature of a constant TPE-Octa-dU gelato r at MGC as low as 0.2 wt%was increased with gel to sol transition,a progressive decrease in the fluorescence intensity was observed.~1 H NMR study in ethanol-d_(6)/H_(2)O revealed the existence of intermolecular hydrogen-bond interaction between uridine nucleobase and triazole moieties.Based on these experiments,thus organogels induced by hydrogen bonding can promote an aggregation-induced emission(AIE)of TPE moiety.Thermoreversible gelation properties have been investigated systematically,including AIE-shapemorphing architecture owing to their unique solid-liquid interface and easy processability.At the same line,the related TPE-EdU derivative which was synthesized from 5-ethynyl-2'-deoxyuridine does not delive r organogels or hydrogels,a nd under similar circumstances TPE moiety of TPE-EdU does not efficiently exhibit AIE phenomenon either.

Novel 1,2,3-triazole-based compounds： Iodo effect on their gelation behavior and cation response

Two new series of 1,2,3-triazole derivatives, with and without iodo substitution, were synthesized and their gelation properties were measured. It was found that the iodo substitution at position 5 of triazole ring could greatly enhance the gelation ability. Scanning electron microscopy and X-ray diffraction reveal that the structures of the organogels from iodo and hydrogenous gelators are totally different, lodo gels are selectively responsive to the stimuli of Hg2＋, whereas hydrogenous gels can respond to Hg2＋ and Cu2＋. Moreover, the reversible gel-sol transition of hydrogenous gels can be controlled by redox reaction or tuned with suitable chemicals. The single crystal analysis of reference compound （C2） suggests that there are intermolecular and intramolecular non-classical hydrogen bonding interactions but no π-π interaction in hydrogenous gelator. The great difference between the two series of compounds results from the iodo effect and implies the existence of halogen bonding interaction in the iodo compounds.

Supramolecular self-assembly of two-component systems comprising aromatic amides/Schiff base and tartaric acid

The gelating properties and thermotropic behaviors of stoichiometric mixtures of aromatic amides 1,2,and the aromatic Schiffbase 3 with tartaric acid(TA)were investigated.Among the three gelators,2-TA exhibited superior gelating ability.Mixture 2-TA exhibits a smectic B phase and an unidentified smectic mesophase during both heating and cooling runs.The results of Fourier transform infrared spectroscopy and X-ray diffraction revealed the existence of hydrogen bonding and rc-ninteractions in 2-TA systems,which are likely to be the dominant driving forces for the supramolecular selfassembly.Additionally,it was established that all of the studied gel self-assemblies and mesophases possess alamellar structure.The anion response ability of the tetrahydrofuran gel of 2-TA was evaluated and it was found that it was responsive to the stimuli of F,Cl,Br,I,AcO.

Wet‑Spinning Knittable Hygroscopic Organogel Fibers Toward Moisture‑Capture‑Enabled Multifunctional Devices

Atmospheric moisture exploitation is emerging as a promising alternative to relieve the shortage of freshwater and energy.Efforts to exploit hygroscopic materials featuring flexibility,programmability,and accessibility are crucial to portable and adaptable devices.However,current two-dimensional(2D)or three-dimensional(3D)-based hygroscopic materials are dif-ficult to adapt to diverse irregular surfaces and meet breathability,which severely hinders their wide applications in wearable and programmable devices.Herein,hygroscopic organogel fibers(HOGFs)were designed via a wet-spinning strategy.The achieved fibers were composed of the hydrophilic polymeric network,hygroscopic solvent,and photothermal/antibacterial Ag nanoparticles(AgNPs),enabling hygroscopic capacity,photothermal conversion,and antibacterial.Owing to the good knittable feature,the HOGFs can be readily woven to adjusted 2D textiles to function as an efficient self-sustained solar evaporator of 4-layer woven HOGF device with a saturated moisture capacity of 1.63 kg m^(-2) and water-releasing rate of 1.46 kg m^(-2) h^(-1).Furthermore,the 2D textile can be applied as a wearable dehumidification device to efficiently remove the evaporative moisture from human skin to maintain a comfortable environment.It can reduce the humidity from 90 to 33.4%within 12.5 min.In addition,the introduction of AgNPs can also endow the HOGFs with antibacterial features,demonstrat-ing significant potential in personal healthcare.

Synthesis and gelation behaviors of five new dimeric cholesteryl derivatives

Five new diacid amides of di-cholesteryl L-glycinates were designed and prepared.The compounds with linkers containing 0,1, 2,3,or 4 methylene units are denoted as 1,2,3,4,and 5,respectively.Their gelation behaviors in 25 solvents were tested as novel low-molecular-mass organic gelators(LMOGs).It was shown that the length of the linker connecting the two-cholesteryl residues in a gelator plays a crucial role in the gelation behavior of the compound.1 gels 11 of the 25 solvents tested at a concentration lower than 1.0%,while 2 gels 17 of the solvents tested.4 and 5,however,gel only 2 and 4 of them,respectively. SEM observation reveals that the lengths of the linkers and the identity of the solvents are the main factors affecting the structures of the aggregates in the gels.Experimentally,a clear linker effect on the microstructures of the gels was observed.As example,the aggregates of 1,2 and 3 in benzene or 1-heptanol adopt structures of thin fibers,rods or lamellas,respectively. Furthermore,it was found that the gelation and aggregation behaviors of 2,3,4,and 5 in DMSO showed an even-odd effect.

A gelable pure organic luminogen with fluorescence-phosphorescence dual emission

Pure organic luminogens with room temperature phosphorescence(RTP) have drawn much attention due to their fundamental importance and promising applications in optoelectronic devices, bioimaging, sensing, etc. Fluorescence-phosphorescence dual emission at room temperature, however, is rarely observed in pure organic materials. Herein, we reported a metal-and heavy-atom free pure organic luminogen with tert-butyl groups, DtBuCZBP, which is ready to form organogels in dimethylsulfoxide(DMSO).It emits prompt and delayed fluorescence, as well as RTP, namely dual emission in as-prepared solid, gels and polymeric films.To the best of our knowledge, it is the first example of metal-and heavy-atom free pure organic gelator with RTP emission. Such unique RTP and moreover dual emission properties in different states make DtBuCZBP a potential material for diverse applications.