Fluorescent Recognition of Small Organic Molecules Based on Supramolecular Aggregation/Deaggregation of Planar Cu(Ⅱ)Coordination Complex

A Cu(II)coordination complex(1)with Schiff ligand derived from diaminomaleonitrile was synthesized and characterized,in which the ligand is rigid,planar and conjugated.The complex 1 displays an interesting fluorescent property relative to solvents which can be turned-on by CH_(2)Cl_(2) and CHCl_(3) solvent molecules.The mechanism of this selective fluorescence emission has been studied based on the crystal structure and the spectrum analysis.The tuning on and off fluorescence of complex 1 can be controlled by the process of supramolecular aggregation/deag-gregation in different solvents.

Aggregation-induced suppression of quantum tunneling by manipulating intermolecular arrangements of magnetic dipoles

The relaxation time under zero field reflects the memory retention capabilities of single-molecule magnets(SMMs)when used as storage devices.Intermolecular magnetic dipole interaction is ubiquitous in aggregates of magnetic molecules and can greatly influence relaxation times.However,such interaction is often considered harmful and challenging to manipulate in molecular solids,especially for high-performance lanthanide single-ion magnets(SIMs).By an elaborately designed combination of ion pairing and hydrogen bonding,we have synthesized two pseudo-D5h SIMs with supramolecular arrangements of magnetic dipoles in staggered and side-by-side patterns,the latter of which exhibits a 104-fold slower zero-field relaxation time at 2 K.Intriguingly,the side-by-side complex exhibits a significantly accelerated magnetic relaxation upon diamagnetic dilution,contrary to the general trend observed in the staggered complex.This strongly reveals the presence of aggregation-induced suppression of quantum tunneling in a side-by-side arrangement,which has not been observed in mononuclear SMMs.By leveraging ion-pairing aggregation and converting to a side-by-side pattern,this study successfully demonstrates an approach to transform a harmful intermolecular dipole interaction into a beneficial one,achieving aτQTM of 980 s ranking among the best-performance SMMs.

Fire-retardant and high-strength polymeric materials enabled by supramolecular aggregates Special Collection:Distinguished Australian Researchers

High-performance polymers have proliferated in modern society across a variety of industries because of their low density,good chemical stability,and superior mechanical properties.However,while polymers are widely applied,frequent fire disasters induced by their intrinsic flammability have caused massive impacts on human beings,the economy,and the environment.Supramolecular chemistry has recently been intensively researched to provide fire retardancy for polymers via the physical barrier and char-catalyzing effects of supramolecular aggregates.In parallel,the noncovalent interactions between supramolecular and polymer chains,such as hydrogen bonding,π-πinteractions,metal-ligand coordination,and synergistic interactions,can endow the matrix with enhanced mechanical strength.This makes it possible to integrate physical-chemical properties and noncovalent interactions into one supramolecular aggregate-based high-performance polymeric system on demand.However,fulfilling these promises needs more research.Here,we provide an overview of the latest research advances of fire-retardant and high-strength polymer materials based on supramolecular structures and interactions of aggregates.This work reviews their conceptual design,characterization,modification principles,performances,applications,and mechanisms.Finally,development challenges and perspectives on future research are also discussed.

Observation of specific ion effects in humus aggregation process

Specific ion effects play a vital role in a variety of colloidal and interfacial processes.However,few studies have reported the specific ion effects in the humus aggregation process,which strongly influence the transport and fate of environmental pollutants.In this study,soil humus colloids were prepared and characterized,and the specific ion effects on humus aggregation in electrolyte solutions were investigated at a variety of concentrations and pH values using dynamic light scattering methods.Activation energy(ΔE),which is known to reflect the dynamics and stability of a colloidal system,was used to quantitatively characterize the specific ion effects.The results showed that given ΔE value of 2.48×10^(3) J mol^(-1) at pH 3.0,the electrolyte concentrations were 91.6,58.2,3.8,and 0.8 mmol L^(-1) for Na^(+),K^(+),Mg^(2+),and Ca_(2+),respectively,thus indicating significant specific ion effects in the humus aggregation process.Most importantly,decreasing the electrolyte concentrations increased the differences in the ΔE value between two cation species with the same valence(i.e.,ΔE_(Na)-ΔE_(K) and ΔE_(Mg)-ΔE_(Ca)),while increasing the pH increased the magnitude of ΔE_(Mg)-ΔE_(Ca).However,the classic Derjaguin,Landau,Verwey,and Overbeek(DLVO)theory and the double layer theory,as well as the currently widely used ionic hydration and dispersion effects,failed to predict the experimentally observed increase in the specific ion effects with decreasing electrolyte concentrations in a quantitative sense.These results have implications for the necessity of involving specific ion effects for a better understanding of humus aggregation and interactions in aqueous and soil systems.

Rapid Self-healing and Strong Adhesive Elastomer via Supramolecular Aggregates from Core-shell Micelles of Silicon Hydroxyl-functionalized cis-Polybutadiene

Liquid trimethoxy silane-functionalized cis-polybutadiene(cis-PB-Si(OMe)3),possessing number-average molecular weights of cis-PB segments(Mn,PB)ranging from 1800 g/mol to 5400 g/mol,with cis-1,4 content of ca.80%and high functionality(>96%)could be synthesized by coordination copolymerization of living cis-PB chain ends with ethenyltrimethoxy-silane with neodymium-based catalytic system.The silicon hydroxyl-functionalized cis-polybutadiene(cis-PB-Si(OH)_(3))-based micelles in water have been achieved by in situ hydrolysis of cis-PB-Si(OMe)_(3)in hexane/water mixture(pH=6.8)at 70℃and by sequential removal of residue hexane.The size of the above micelles with soft elastic cis-PB cores could be remarkably enlarged by loading SiO_(2)nanoparticles on their surfaces via hydrogen bonding interaction.Giant supramolecular long chain aggregates or networks formed by hydrogen bonding interaction and possible O—Si—O chemical bonds between cis-PB-Si(OH)3-based micellar surfaces had relatively large size and thus precipitated from water after several months of storage,leading to production of cis-PB-Si(OH)_(3)solid elastomer with extremely low T_(g)at−107.0℃.The left cis-PB-Si(OH)_(3)-based micelles in water with relatively small size gradually formed the water-insoluble cis-PB-Si(OH)_(3)-based supramolecular aggregates or networks.The cis-PB-Si(OH)_(3)-based supramolecular elastomer exhibited excellent self-healing property within 60 s at 25℃.The elastomer(20 mg)in a joint of 25 mm×30 mm(2.7 mg/cm^(2))provided very strong adhesion for two pieces of glass and the bound glass keep unchanged at room temperature for 98 h even hung with 100 g of steel column below.The cis-PB-Si(OH)3-based supramolecular elastomer would have potential applications in adhesives,self-healing materials,damping materials and elastic materials.

Secondary ligand engineering of nanoclusters:Effects on molecular structures,supramolecular aggregates,and optical properties

Developing new templates to evaluate the ligand engineering effect in manipulating nanoclusters from both molecular and supramolecular aspects remains highly desired in cluster science because it allows for an in-depth understanding of structure-property correlations.We herein presented the secondary ligand(i.e.,the phosphine ligand)engineering based on an Ag_(29) nanocluster template and its dual effects on intracluster structures and intercluster aggregates.The“dissociationcombination equilibrium”of phosphine ligands on the nanocluster surface was controlled by tailoring the C-H…πinteractions within the ligand shell,which led to the fabrication of a family of[Ag_(29)(BDT)_(12)(PR_(3))_(x)]^(3-)nanoclusters.On the molecular level,the dissociation of phosphine ligands contracted the nanocluster framework,while the overall configuration of[Ag_(29)(BDT)_(12)]^(3-)was retained.On the supramolecular level,the complete dissociation of phosphine ligands yielded a bare nanocluster,which followed a chiral crystallization mode,and its crystals displayed high optical activity,derived from circular dichroism and circularly polarized luminescence characterizations.Overall,this work presents the peripheral ligand effects in directionally controlling intracluster configurations and intercluster aggregations,which hopefully benefit future design and preparation of new nanoclusters or cluster-based nanomaterials with customized structures and performances.

Isolated supramolecules on surfaces studied with scanning tunneling microscopy

To date, supramolecular chemistry is an ever growing research field owing to its crucial role in molecular catalysis, recognition, medicine, data storage and processing as well as artificial photosynthetic devices.Different isolated supramolecules were prepared by molecular self-assembly on surfaces. This review mainly focuses on supramolecular aggregations on noble metal surfaces studied by scanning tunneling microscopy, including dimers, trimers, tetramers, pentamers, wire-like assemblies and Sierpin′ ski triangular fractals. The variety of self-assembled structures reflects the subtle balance between intermolecular and molecule–substrate interactions, which to some extent may be controlled by molecules, substrates and the molecular coverage. The comparative study of different architectures helps identifying the operative mechanisms that lead to the structural motifs. The application of these mechanisms may lead to novel assemblies with tailored physicochemical properties.

Discovery,characterization and stability evaluation of self-assembled submicroparticles in chrysanthemum tea infusions

Chrysanthemum tea infusions are famous and nutritious beverages worldwide.The results showed that numerous negatively charged spherical particles of 60–1000 nm in diameter generally existed in all chrysanthemum tea infusions prepared from 9 kinds of chrysanthemums for tea use.Taking Chrysanthemum morifolium ‘Hangbaiju ’ tea infusion as an example,crushing,heating and increasing flower-to-water ratio were three strategies to prepare optimal submicroparticles with the smallest mean hydrodynamic diameter as 288.40 nm and polydispersity index as 0.25.The submicroparticles were stable when temperature change,dialysis,centrifugation,storage,pH change (2–9) and ionic strength change were applied but unstable when freeze-thaw,lyophilization,ultrafiltration,concentration and pH change (10) were applied.Polysaccharides and phenolics were dominant components of submicroparticles which were maintained by hydrogen bonds and hydrophobic interactions among polysaccharides and phenolics.This study provided a novel perspective to decipher and control supramolecular aggregation in chrysanthemum tea infusions for rational manufacturing.