Recent Advances in Pure-Organic Host-Guest Room-Temperature Phosphorescence Systems Toward Bioimaging

Organic room-temperature phosphorescence(RTP)materials have garnered considerable attention in the fields of biosensing,optoelectronic devices,and anticounterfeiting because of their substantial Stokes shifts,tunable emission wavelengths,and prolonged lifetimes.These materials offer remarkable advantages for biological imaging applications by effectively reducing environmental autofluorescence and enhancing imaging resolution.Recently,host-guest systems have been employed as efficient approaches to fabricate pure-organic RTP materials for bioimaging,providing benefits such as controllable preparation and flexible modulation.Consequently,an increasing number of corresponding studies are being reported;however,a comprehensive systematic review is still lacking.Therefore,we summarize recent advances in the development of pureorganic RTP materials using host-guest systems with regard to bioimaging,including rigid matrices and sensitization.The challenge and potential of RTP for biological imaging are also proposed to promote the biomedical applications of organic RTP materials with excellent optical properties.

Host-guest supramolecular interaction behavior at the interface between anode and electrolyte for long life Zn anode

The hydrogen evolution reaction (HER) and dendrite growth associated with Zn anode have become the main bottlenecks for the further development of zinc ion batteries (ZIBs).In this work,the electrochemical activity of H_(3)O^(+) is inhibited by the supramolecular host–guest complex composed of H_(3)O^(+) as guest and 18-crown-6 as host.The even Zn plating is induced by the host–guest complex electrostatic shielding layer on Zn anode,as detected by in-situ optical microscopy.The lamellar Zn is plated which profits from the improved Zn plating behavior.Density functional theory (DFT) calculation presents the stable structure of complex.The less produced H_(2) content is monitored online by a mass spectrometer during Zn plating/stripping,which indicates HER can be hampered by the host–guest behavior.Thus,the ZIBs with long life and high Coulombic efficiency are achieved via introducing 18-crown-6.The proposed host–guest supramolecular interaction is expected to facilitate the furthermore development of Zn batteries.

Highly Luminescent Host-Guest Systems Based on Zeolite L and Lanthanide Complexes

Supramolecular incorporation of lanthanide complex has been obtained by loading of organic ligand into Eu3+-exchanged zeolite L. This was achieved by a two-step procedure: (1) zeolite L was ion-exchanged with Eu(Ⅲ) ions; (2) organic ligand was then loaded into the channels of the Eu3+-exchanged zeolite by gas diffusion procedure. Loading of ligand into the channels of zeolite L was confirmed by element analysis. Luminescence spectroscopy has confirmed that lanthanide complex are formed in the nanochannels of zeolite L crystals. In addition to the sharp emissions of lanthanide ions, broad band ranged from 350～500 nm can also be observed. This study provides alternative method for fabricating full-color display materials.

Host-guest interaction of β-cyclodextrin with isomeric ursolic acid and oleanolic acid:physicochemical characterization and molecular modeling study

Ursolic acid(UA) and oleanolic acid(OA) are insoluble drugs. The objective of this study was to encapsulate them into β-cyclodextrin(β-CD) and compare the solubility and intermolecular force of β-CD with the two isomeric triterpenic acids. The host-guest interaction was explored in liquid and solid state by ultraviolet-visible absorption,1H NMR, phase solubility analysis, and differential scanning calorimetry, X-ray powder diffractometry, and molecular modeling studies. Both experimental and theoretical studies revealed that β-CD formed 1: 1 water soluble inclusion complexes and the complexation process was naturally favorable. In addition, the overall results suggested that ring E with a carboxyl group of the drug was encapsulated into the hydrophobic CD nanocavity. Therefore, a clear different inclusion behavior was observed, and UA exhibited better affinity to β-CD compared with OA in various media due to little steric interference, which was beneficial to form stable inclusion complex with β-CD and increase its water solubility effectively.

Insight into the effects of electrochemical factors on host-guest interaction induced signature events in a biological nanopore

The signature events caused by host-guest interactions in the nanopore system can be used as a novel and characteristic signal in quantitative detection and analysis of various molecules.However,the effect of several electrochemical factors on the host-guest interactions in nanopore still remains unknown.Here,we systematically studied host-guest interactions,especially oscillation of DNA-azide adamantane@cucurbit[6]inα-Hemolysin nanopore under varying pH,concentration of electrolytes and counterions(Li+,Na+,K+).Our results indicate correlations between the change of pH and the duration of the oscillation signal.In addition,the asymmetric electrolyte concentration and the charge of the counterions affects the frequency of signature events in oscillation signals,and even the integrity of the protein nanopore.This study provides insight into the design of a future biosensing platform based on signature oscillation signals of the host-guest interaction within a nanopore.

Microcalorimetric study on host-guest complexation of naphtho-15-crown-5 with four ions of alkaline earth metal

Thermodynamic parameters of complexation of naphto- 15-crown-5 with four alkaline earth ions in aqueous media was determined using titration microcalorimetry at 298.15 K. The stability of the complexes, thermal effect and entropy effect of the complexation is discussed on the basis of the guest ions structure and the solvent effect. The stability constants tendency to vary with ion radius was interpreted. Complex of naphtha-15-crown-5 with calcium ion is very stable due to the synergism of static electric interaction and size selectivity between the host and the guest.

Synthesis and Characterization of the Host-Guest NanocompositeMaterial Zeolite Y-Iron Bipyridine

This paper reports the synthesis of host-guest nanocomposite material [Fe(bpy)(3)]Y2+ (where bpy=2,2'-bipyridine) using the flexible ligand method. X-ray diffraction analysis. adsorption technique, and cyclic voltammetry were used to characterize the material. The results show that [Fe(bpy)(3)](2+) has been entrapped in the supercage of zeolite, its electron transfer is realized by electron hopping of [Fe(bpy)(3)](2+) within the supercage of zeolite.

Characteristic Studies of Arylated β-Cyclodextrins in Host-Guest Complexation with Small Molecules

The aryl moiety which was bonded as a functional group on the primary alcohol side ofβ-CD or the secondary alcohol side of β-CD or the secondary alcohol side of β-CD with anethylenediamino chain could show remarkable different molecular recognition abilities in thecomplexation with small molecular guests such as alkanes, cycloketones etc.

A Spectrophotometric Study on the Host-Guest Complexation of β-Cyclodextrin with 3-Indolyl Acetate in Dilute Aqueous Solution by Determining Solubility of Guest Substance

3-Indolyl acetate can be soluhilized in dilute aqueous solution of beta cy clodextrin. dueto the formation of host-guest complex through hydrophobic interaction between the indolyl groupand the inside cave of the cyclodextrin molecule. The thermodynamic pararneters of thecomplexing process can be estimated utilizing the spectrophotometric data.

Structure Studies on Host-Guest Recognition Sensory Systems

Rhodamine B-ethylenediamine-beta-cyclodextrins (RhB-beta-CDen) and rhodamine B-beta-cyclodextrins (RhB-beta-CD) form inclusion complexes with many guest molecules, which can be used as nucleic acid probe. In this paper we determined the most stable conformations of RhB-beta-CDen and RhB-beta-CD by molecular mechanics and dynamics simulation. The interaction between RhB-beta-CDen and two guest molecules, 1-borneol and cyclohexanol, have been investigated both theoretically and experimentally. The results show that the interaction between borneol and RhB-beta-CDen is stronger than that between cyclohexanol and RhB-beta-CDen.

Preparation, Characterization and Optical Properties of Host-guest Nanocomposite Material Mordenite-silver Iodide

Silver iodide nanoclusters were successfully prepared in the channels of mordenite by a heat diffusion method. Powder X ray diffraction, adsorption technique and infrared spectroscopy were used to characterize the prepared materials, which showed that the guest silver iodide had been encapsulated in the channels of mordenite. The optical properties of the solid phase diffuse reflectance absorption of nanocomposite material NaM AgI were studied, showing that the absorption bands of the diffuse reflectance absorption of the prepared material moved to the region of high energy. The absorption peak of the material prepared shifted to the region of high energy. Namely, blue shift was caused. This has demonstrated the incorporation of silver iodide into the channels of the zeolite. We observed the luminescence and surface photovoltage spectra of NaM AgI sample, proposing the mechanisms of the photoluminescence and photovoltaic responses.

Out-of-Equilibrium Assembly Based on Host-Guest Interactions

The field of supramolecular chemistry is rapidly progressing,transitioning from the creation of thermodynamically stable systems found in local or global minima on the free energy landscape to the development of out-of-equilibrium systems that rely on chemical reactions to establish and maintain their structures.Over the past decade,numerous artificial out-of-equilibrium systems have been devised in various domains of supramolecular chemistry,many of which have been extensively reviewed.However,one area that has received limited attention thus far is the use of out-of-equilibrium processes to regulate host-guest interactions.This minireview aims to address this gap by exploring the construction of out-ofequilibrium systems based on host-guest complexation,which likely employs similar strategies to those employed in analogous noncovalent interactions.The review begins with a summary of these shared strategies.Subsequently,it discusses representative publications that exemplify these strategies and classifies thembased onwhich component is being modulated-host,guest,or competitive molecules.Through this examination,our objective is to shed light on the design of out-of-equilibrium systems relying on host-guest interactions and provide valuable insights into the preparation strategies for various transient materials.

Redox-Active Dihydrophenazine-Based Macrocycle:Synthesis,Conformation-Adaptive Behavior and Host-Guest Complexation with Tetracyanoquinodimethane

A novel macrocycle based on conformation-adaptive and electron-rich dihydrophenazine was designed and synthesized.On the one hand,the macrocycle showed host-guest interactions with tetracyanoquinodimethane(TCNQ)driving by charge transfer interaction between them.Meanwhile,host-guest complexation was accompanied by fluorescence quenching and conformational change of the macrocycle.On the other hand,the oxidation of the macrocycle resulted in its diradical cation analogue and induced the release of the guest molecule TCNQ,thereby accomplishing reversible binding dynamics.Therefore,this work wellillustrates the chemical and structural versatility of dihydrophenazine in the synthesis of macrocycles and their host-guest chemistry.

Synthetic host-guest pairs as novel bioorthogonal tools for pre-targeting

Due to its simplicity, high efficiency, and chemo-selectivity, bioorthogonal chemistry has shown a great application potential in pre-targeting.Currently, four bioorthogonal pairs as targeting tools, including (strept)avidin/biotin, antibody/antigen, oligonucleotide hybridization and IEDDA tools, have been developed and applied in targeted delivery.Nevertheless, all of these tools still suffer from some limitations, such as difficult modification, biochemical fragility and larger molecular weight for biological association tools, as well as chemical instability for IEDDA tools.Synthetic host-guest pairs with relatively small molecular sizes not only possess strong chemical stability, but also have the features of fast conjugation rate, tunable binding affinity , easy modification, and high chemo-selectivity.Consequently, they can be used as a novel non-covalent bioorthogonal tool for pre-targeting.In order to further promote the development of host-guest pairs as novel bioorthogonal tools for pre-targeted delivery, we firstly calculate their conversion rate to make researcher aware of their unique advantages;next, we summarize the recent research progress in this area.The future perspectives and limitations of these unique tools will be discussed.This review will provide a systemic overview of the development of synthetic host-guest pairs as novel bioorthogonal tools for pre-targeting, and may serve as a “go for” resort for researchers who are interested in searching for new synthetic tools to improve pre-targeting.

Increase of chiral sensing ability in host-guest chemistry by magnetic anisotropy

Enantiomeric molecules generally play distinct functions in chemistry,biology,and pharmacology.Similar physical and chemical properties of chiral analytes lay difficulty in discrimination and quantification of the enantiomers.We report herein an efficient approach of increasing the chiral sensing ability ofβ-cyclodextrin(β-CD),a widely used host molecule,in the hostguest chemistry by magnetic anisotropy.A rigid and chiral lanthanide binding tag was attached to theβ-CD to amplify the changes of nuclear magnetic resonance(NMR)signals in the host-guest recognition process.The installation of the paramagnetic lanthanide ion inβ-CD greatly enhances the enantiomeric discrimination up to 30-fold in comparison with the diamagneticβ-CD reference.In addition,the magnitude of the paramagnetic effects is tunable according to the diverse range of paramagnetic strength of the lanthanide series.The reported method significantly increases the chiral sensing ability ofβ-CD,which can be applied to other host molecules.The transferred paramagnetic effects,pseudocontact shifts(PCSs)and paramagnetic relaxation enhancements(PREs),from the host to the guest molecules,are valuable structural restraints to determine the absolute stereochemistry of the chiral analytes.The strategy does not need modification of the analytes and is complementary to the reported analytical methods that rely on the functionalization of the chiral analytes.

Achieving highly efficient long-wavelength phosphorescence emission of large singlet-triplet energy gap materials by host-guest doping

High-efficiency long-wavelength phosphorescence emissions of large singlet-triplet energy gap(ΔE_(ST))materials are essential for applications in biology and display.However,few long-wavelength phosphorescence emissions of largeΔE_(ST)materials have been reported due to the weak spin-orbit coupling(SOC)and strong non-radiative transitions.Herein,we develop a strategy to achieve highly efficient long-wavelength room temperature phosphorescence(RTP)emission of largeΔE_(ST)materials,which display bright red RTP emission with above 400μs lifetime and 6.5%phosphorescent quantum efficiency.Our experiments and theoretical calculations reveal that the fishbone-like packing and the zig-zag interactions provide favorable conditions for suppressing the non-radiative transitions of triplet state excitons,and heavy atoms effectively promote the intersystem crossing(ISC)process for highly efficient long-wavelength phosphorescence emission.The universality of the method for highly efficient long-wavelength RTP emission of largeΔE_(ST)materials was further investigated in various guests.Moreover,these materials with largeΔE_(ST)manifest the advantages of large color contrast on the display and utilization potentiality in information encryption.This strategy paves the way for the high contrast display and development of information encryption with RTP emission.

Engineering singlet and triplet excitons of TADF emitters by different host-guest interactions

Understanding the host-guest interactions for thermally activated delayed fluorescence(TADF)emitters is critical because the interactions between the host matrices and TADF emitters enable precise control on the optoelectronic performance,whereas technologically manipulating the singlet and triplet excitons by using different kinds of host-guest interactions remains elusive.Here,we report a comprehensive picture that rationalizes host-guest interaction-modulated exciton recombination by using time-resolved spectroscopy.We found that the early-time relaxation is accelerated in polar polymer because dipole-dipole interaction facilitates the stabilization of the 1CT state.However,an opposite trend is observed in longer delay time,and faster decay in the less polar polymer is ascribed to theπ-πinteraction that plays the dominant role in the later stage of the excited state.Our findings highlight the technological engineering singlet and triplet excitons using different kinds of host-guest interactions based on their electronic characteristics.

Detection of Oxygen Based on Host-Guest Doped Room-Temperature Phosphorescence Material

Quantitative oxygen detection,especially at low concentrations,holds significant importance in the realms of biology,complex environments,and chemical process engineering.Due to the high sensitivity and rapid response of the triplet excitons of phosphorescence to oxygen,pure organic room-temperature phosphorescence(RTP)materials have garnered widespread attention in recent years for oxygen detection.However,simultaneously achieving ultralong phosphorescence at room temperature and quantitative oxygen detection from pure organic host-guest doped materials poses challenges.The d ensely packed materials may decrease non-radiative decay to increase the phosphorescence,but are unsuitable for oxygen diffusion in oxygen detection.Herein,the oxygen sensitivity of host-guest doped RTP materials using 4-bromo-N,N-bis(4-(tertbutyl)phenyl)aniline(TPABuBr)as the host and 6-bromo-2-butyl-1H-benzo[de]isoquinoline-1,3(2H)-dione(NIBr)as the guest was developed.The doped material exhibits fluorescence-phosphorescence dual-emission behavior at room temperature.The tert-butyl groups in TPABuBr facilitate appropriate intermolecular spacing in the crystal state,enhancing oxygen permeability.Therefore,oxygen penetration can quench the phosphorescence emission.The observed linear relationship between the phosphorescence intensity of the doped material and the oxygen volume fraction conforms to the Stern-Volmer equation,suggesting its potential for quantitative analysis of oxygen concentration.The calculated limit of detection is 0.015%(φ),enabling the analysis of oxygen with a volume fraction of less than 2.5%(φ).Moreover,the doped materials demonstrate rapid response and excellent photostability,indicating their potential utility as oxygen sensors.This study elucidates the design and characteristics of NIBr/TPABuBr doped materials,highlighting their potential application in oxygen concentration detection and offering insights for the design of oxygen sensors.

Highly two-photon and X-ray excited long-persistent luminescence in a crystalline host-guest aggregate

As a unique type of supramolecular self-assemblies,crystalline host-guest aggregates have attracted extensive interests in multiple application fields.Herein,a crystalline host-guest aggregate LIFM-HG1 was obtained with curcubit[8]uril as the host and carboxypyridinium salt as the guest.Single-crystal structural analysis indicates that the presence of abundant weak interactions in LIFM-HG1 provides a rigid environment for the guest molecule and effectively blocks the external quenchers.Spectral analysis and theoretical calculations confirm the presence of robust triplet energy levels in LIFM-HG1.Even more impressively,the intersystem crossing channels of the guest molecules are greatly opened up after the formation of the crystalline host-guest aggregate,resulting in a large k_(isc)of 6.70×10^(7)s^(−1)at room temperature for LIFM-HG1(which is∼0 for pure guest),leading to fascinatingmultichannel(including one-photon,two-photon,and X-ray)excited LPL properties.In addition,the crystalline LIFM-HG1 has a much higher triplet state luminescence efficiency under X-ray and two-photon excitation than that under single-photon excitation(A_(P)/A_(F)=86.8,44.8,10.7 under the three circumstances,respectively).And the phosphorescent emission intensity of LIFM-HG1 is 27.6 times higher than that of the crystalline guest under X-ray excitation.As a result,LIFM-HG1 shows a long afterglow retention time under both single-and two-photon excitation,and an impressive afterglow retention time of 1 s under X-ray excitation.Furthermore,the excellent lysosomal targeting and low cytotoxicity by the formation of host-guest aggregate makes LIFM-HG1 promising to be used as a novel lysosomal-targeted two-photon excited phosphorescent tracer.

Host-Guest Strategy Enabling Nonhalogenated Solvent Processing for High-Performance All-Polymer Hosted Solar Cells

The power conversion efficiencies(PCEs)of all-polymer solar cells(all-PSCs),usually processed from low-boiling-point and toxic sol-vents,have reached high values of 18%.However,poor miscibility and uncontrollable crystallinity in polymer blends lead to a nota-ble drop in the PCEs when using green solvents,limiting the practical development of all-PSCs.Herein,a third component(guest)BTO was employed to optimize the miscibility and enhance the crystallinity of PM6/PY2Se-F host film processed from green solvent toluene(TL),which can effectively suppress the excessive aggregation of PY2Se-F and facilitate a nano-scale interpenetrating net-work morphology for exciton dissociation and charge transport.As a result,TL-processed all-polymer hosted solar cells(all-PHSCs)exhibited an impressive PCE of 17.01%.Moreover,the strong molecular interaction between the host and guest molecules also en-hances the thermal stability of the devices.Our host-guest strategy provides a unique approach to developing high-efficiency and stable all-PHSCs processed from green solvents,paving the way for the industrial development of all-PHSCs.