Bucket Effect to Improve Third-Order Nonlinear Optical Response on Metal-Heteroaromatic Compounds

Carbolong compounds as a metal-heteroaromatic compound with both organometallic properties andπ-conjugated systems exhibit great potential in organic catalysis and optoelectronic devices.In this work,for the first time,the“Bucket Effect”is revealed to promote the third-order nonlinear optical(NLO)performance in metal-heteroaromatic compounds.We have successfully constructed and investigated a series of novel metallapentalenes with higher third-order NLO performance benefited from the“Bucket Effect”.Meanwhile,aromaticity and electron−hole analysis further confirm the internal homogeneity of organometallic rings,reduced bandgap,and enhanced low-energy peak response resulted in the enhanced third-order NLO effects.The success of this work is discovering an emerging material library of high third-order NLO effects,and illustrating the feasibility of engineering the high response metal-heteroaromatic optical devices at the electronic structure level.

A chiral SrSi_(2)(srs)superstructure constructed by a dual interaction system showing isotropic electrical conductivity

Most porous conductive frameworks are highly anisotropic in their structures thus leading to anisotropic charge transport.Here we report a supramolecular self-assembly which is constructed by intermolecular hydrogen bonding andπ···πinteractions.This material features a chiral,porous,cubic framework structure withπ-stacked helical columns along all of the three Cartesian coordinates.As a result,isotropic charge transport with an electrical conductivity(σ)of 2.1×10^(–7)S/cm is achieved.By achieving isotropic charge transport in aπ-stacked supramolecular assembly,these results provide a new type of isotropic conductive framework materials alternative to conductive metal-organic frameworks(MOFs).

Homochiral design of titanium-organic cage for circularly polarized luminescence-based molecular detection

Post-assembly modification strategy is used as an effective approach to improve the functional applications of metal-organic cages. The active vertex of the racemic tetrahedral Ti4L6(L = embonate) cages traps four chiral diamine chelated dinuclear silver ions, obtaining homochiral cages which exhibit helical perovskite stacks. Such a surface modification engineering enables the structural precise cages presenting homochirality and circularly polarized luminescence(CPL) response, further achieving enantioselective recognition toward chiral Camphorquinone molecules and displaying enhanced temperature-dependent effects of CPL output.

Breaking Mirror Circularly Polarized Luminescence of Chiral Metal-Organic Frameworks by High-Pressure Stimulation

Understanding high-pressure-stimulated circularly polarized luminescence(CPL)of enantiomers remains a challenging but significant task in fundamental research and optical applications.Here,we combined in situ high-pressure photoluminescence with circularly polarized light to study how high pressure stimulated the CPL of crystalline enantiomers.Chiral lanthanide(Ln)-tartrate(Tar)metal-organic frameworks(MOFs;Ln=Eu,Tb)were synthesized to study their CPL from atmospheric pressure to 10 GPa.Under atmospheric pressure,D-and L-Eu(Tar)showed strong andmirror CPL.CPL intensity changes,emission wavelength shifts,and signal inversions were induced by increasing pressure.Note that the D-Eu(Tar)enantiomer showed strong CPL with a maximal dissymmetric factor(g_(lum))of 0.69 under 3 GPa,which is much higher than that under atmospheric pressure and of other reported MOF-based CPL materials.More interestingly,D-and L-Ln(Tar)enantiomers display obvious asymmetric CPL signals with increasing pressure,demonstrating that high pressure can break the mirror CPL of the MOF enantiomers.Our findings provide a critical understanding on in situ high-pressure CPL of chiral materials and establish a new optical phenomenon where high pressure can break the mirror CPL of enantiomers.

Atomically Precise Titanium–Oxo Nanotube with Selective Water Adsorption and Semiconductive Behaviors

We report the first example of carbon nanotube(CNT)-like assembly of the titanium(Ti)framework,Ti oxo inorganic cluster(Ti6O6)hexagonal rings into a titanium oxide(Ti–O)nanotube,prepared by ionothermal synthesis.As determined by single-crystal X-ray diffraction analysis,the Ti–O nanotube arrays,stabilized by sulfate ligands,assumed proper parallel alignment with each other and were separated by supramolecular interactions with surrounding EMIm(1-Ethyl-3-methylimidazolium)counter cations.Our stability studies indicated that the Ti–O nanotube obtained is indeed stable in air and various solvents.Also,it could maintain its structure upon heating to∼300°C.Moreover,inside the pores of the Ti–O nanotubes,a rare water molecules nanoconfinement behavior was observed at room temperature.Further,our current developed Ti–O nanotube arrays exhibited selective water adsorption over methanol and ethanol,showing potential applications for miscible solvents separations.Finally,these Ti–O nanotubes demonstrated typical semiconductive characteristics,with the electrical conductivity increasing four orders of magnitude,ranging from 3.15×10^(−10)–1.03×10^(−6)S/cm,as the temperature increased from 35 to 135°C.This work represents a milestone in constructing inorganic Ti–O nanotube arrays with atomically precise structural information for applications as visible-lightinduced photocatalysts,semiconductors,sensors,and optoelectronics.

Surface-Oriented Assembly of Cyclodextrin Metal-Organic Framework Film for Enhanced Peptide-Enantiomers Sensing

Oriented metal-organic framework(MOF)films are attracting great attention due to their fascinating physicochemical properties and unique functionalities.Here,we report an[110]-oriented biomolecularγ-cyclodextrin(γCD)MOF film with arrayed CD channels running perpendicular to the substrate surface.This sophisticated architecturewas realized by combining liquid phase epitaxial layer-by-layer(lbl)methods with aγCD-based thiol self-assembled monolayer(SAM)functionalized surface.This first demonstration of the lbl method for MOF growth from aqueous conditions yielded oriented,highly homogeneous,and chiralγCD-SURMOFs(surfacecoordinated MOFs)with tunable thickness.Using a quartz crystal microbalance(QCM)to monitor adsorption of biomolecules,we demonstrated thatγCD-SURMOF provides highly-efficient recognition of tripeptide enantiomers(Tyr-(L-Ala)-Phe vs Tyr-(D-Ala)-Phe),clearly outperformingγCD(SH)_(8) SAMs as well as polycrystalline,mixed-orientationsγCDMOF film.The presence of well-alignedγCD-channels enables highly efficient transport channels with large adsorption capacity and fast loading,along with high enantioselectivity.In addition,the fast and highly specific loading rates allow for the realization of highly specific sensors for biomolecules with short response times.