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The need for carbon‐neutralization technologies has prompted significant interest in developing materials for CO2 reduction. Donor–acceptor (D–A) based flexible porous coordination polymers {[Zn(o‐phen)(ndc)].(guest)}n, (guest = anthracene = 1‐Ant, and pyrene = 1‐Pyr) are reported as photocatalysts for CO2RR, yielding higher order CH4 product. Electron‐rich anthracene (Ant) and pyrene (Pyr) guests are confined within nanopores, forming D–A charge transfer (CT) complexes with o‐phen ligand of the host. CT interaction enhances visible light absorption and modulates excitonic properties of the photocatalyst by electronic push‐pull effect (exciton binding energy 87 meV for 1‐Ant and 104 meV for 1‐Pyr). Electron donation capability varies from Pyr to Ant, affecting catalytic properties; 1‐Ant yields 1.24 mmolg−1 of CH4 (0.47 mmolg−1 for 1‐Pyr) with CO as minor product. A mixed‐metal multivariate PCP {[Zn0.55Co0.45(o‐phen)(ndc)].(Ant)}n, (1′‐Ant) prepared based on solid‐solution approach by substituting Zn(II) with redox‐active Co(II) enhances CH4 production (2.79 mmolg−1, ≈94% selectivity). D–A CT complex harvests visible light and channels electrons to Co(II) for CO2RR. In situ DRIFTS and theoretical studies elucidate Co(II) site's role in CO2 binding and stabilizing reaction intermediates. This work underscores guest‐modulated electron transfer in PCPs for tailoring catalytic properties by introducing a redox‐active metal in a multivariate approach. [ABSTRACT FROM AUTHOR]

Two new structural motifs within the class of heteroleptic PdnAnBn assemblies, namely syn‐cis‐Pd3A3B3 bowls and bowl‐ (syn) or saddle‐ (anti) shaped cis‐Pd4A4B4 rings are introduced. All of the ten examples share a common longer fluorenone‐based bis‐monodentate ligand, equipped with meta‐pyridine donor groups. The ring size (3‐ vs. 4‐membered) and conformational preference (bowl vs. saddle) are controlled by the choice of the shorter ligand. These carry para‐pyridine donors, different aromatic backbones (benzene, thiophene or selenophene) and either no or small or bulky endohedral substituents, serving to control the nuclearity of the heteroleptic rings through different effects (ligand angle, charge distribution or backbone bulk). Moreover, the luminescence of the fluorenone ligand is conserved in the formed architectures. Emission intensity as well as host–guest properties vary depending on the inward‐pointing functions. All Pd3A3B3 assemblies are shown to bind chiral guest BINOL bis‐sulfonate which imparts its chirality to the entire host–guest complex. This results in a guest‐induced circular dichroism (CD) and circularly polarized luminescence (CPL) with dissymmetry factor glum up to 10−3. [ABSTRACT FROM AUTHOR]

Photo‐responsive organic crystals, capable of converting light energy into chemical energy to initiate conformational transitions, present an emerging strategy for developing lightweight and versatile smart materials. However, visible light‐triggered tailored guests capture and release behaviors in all‐organic solids are rarely reported. Here, we introduce a photoreactive crystalline boron‐nitrogen (B←N) host adduct with the ability to undergo [2+2] photocycloaddition upon 447 nm light exposure. This process facilitates single‐crystal‐to‐single‐crystal (SCSC) photodimerization in the mother liquor, maintaining the original B←N host structure. Weakened intermolecular interactions within the photodimer host contribute to fast guest release in air under irradiation. Furthermore, the dynamic B←N bonds enable reversible transformations between organic host adducts and adduct cocrystals under the solvent‐induced allosteric effect. As a result, four B←N host adduct crystals containing individual alkane guest are easily obtained and exhibited the ability of photo‐controlled alkane release. Therefore, the integration of photo reactivity and structural transformation within B←N host adduct enables customized capture and release of guest molecules. [ABSTRACT FROM AUTHOR]

In this study, we reported the construction of 3D supramolecular polymeric networks using per‐imidazole pillar[5]arene (DIMP5) as a host and 1,4‐diiodotetrafluorobenzene (L) as a halogen bond donor in chloroform. The supramolecular polymerization process was characterized by 1H NMR, 19F NMR spectroscopy, and X‐ray single crystal analysis. The C─I⋯N distance (2.78 Å) and C─I⋯N angle (177°) clearly indicated the formation of halogen bonds in the crystal structure. Meanwhile, by introducing adiponitrile (G) as the guest, a supramolecular polymerization of pseudo[2]rotaxanes was also prepared, which was driven by DIMP5‐based host–guest complexations and halogen bonding interactions. [ABSTRACT FROM AUTHOR]

This study employed a computational approach, particularly Density Functional Theory at B3LYP−D3/6‐31+G(d) level to design two new classes of three‐dimensional (3D) Lantern Organic Frameworks (LOFs) materials based on trisilasumanene and porphyrin core building units. Particularly, we detail strategies for transitioning from 1D‐LOF nanowires to extended 3D structures: first by connecting planar‐molecule base units of trisilasumanene or porphyrin using benzene‐based linkers, and then connecting silicon anchoring atoms on the bases with other bases that are vertically stacked by sp3‐hydrocarbon chains. The 3D‐LOF structures are designed to have different pore sizes through the use of various bases, bridges, and linkers. Comparisons of electronic properties of these 3D structures lead to one designing rule. That is, the gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the 3D materials depends only on its base and is nearly independent of the stack size or the length of the sp3‐hydrocarbon bridges. Additionally, connecting base units with linkers also extends π‐electron conjugation system leading to a reduction in HOMO‐LUMO gap. For instance, linking two trisilasumanene molecules significantly narrows HOMO‐LUMO gap by 1.75 eV while stacking these bases vertically and connecting them by linear pentane‐based bridges yield insignificant change to the gap. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Macrocyclic compounds are of great interest for their ability to capture guest molecules into their cavities. In particular, host‐guest interaction plays a crucial role in the formation of supramolecular compounds. Herein, two host‐guest supramolecular compounds, [Al8(OH)8(L)16]·2HL (HL@AlOC‐166, HL = 4‐Iodobenzoic acid) and [Al8(OH)8(L)8(L1)8]·2DMF (DMF@AlOC‐166, HL1 = isoamyl alcohol), are acquired by introducing different types of guest components based on the internal pore cavities of the aluminum molecular ring [Al8(OH)8(L)16] (AlOC‐166). The inclusion of these guests is attributed to the presence of abundant hydrophilic OH serving as the hydrogen bond donors inward the ring cavity. Host‐guest compounds usually exhibit superior nonlinear optical (NLO) response due to the existence of guest molecules that could change symmetry, dipole moments, charge distributions, etc. Unexpectedly, the AlOC‐166 achieved the best NLO results, although it had no guest molecules inside its molecular ring, which breaks the traditional concept. The reason for this trend can be explained by the difference in intermolecular force rather than intramolecular interaction, mainly related to the amount and strength of π···π and C—I···π interactions in different compounds. This work investigates the effect of host‐guest interaction on NLO, representing a new perspective for designing optical limiting materials. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Macrocyclic compounds are of great interest for their ability to capture guest molecules into their cavities. In particular, host‐guest interaction plays a crucial role in the formation of supramolecular compounds. Herein, two host‐guest supramolecular compounds, [Al8(OH)8(L)16]·2HL (HL@AlOC‐166, HL = 4‐Iodobenzoic acid) and [Al8(OH)8(L)8(L1)8]·2DMF (DMF@AlOC‐166, HL1 = isoamyl alcohol), are acquired by introducing different types of guest components based on the internal pore cavities of the aluminum molecular ring [Al8(OH)8(L)16] (AlOC‐166). The inclusion of these guests is attributed to the presence of abundant hydrophilic OH serving as the hydrogen bond donors inward the ring cavity. Host‐guest compounds usually exhibit superior nonlinear optical (NLO) response due to the existence of guest molecules that could change symmetry, dipole moments, charge distributions, etc. Unexpectedly, the AlOC‐166 achieved the best NLO results, although it had no guest molecules inside its molecular ring, which breaks the traditional concept. The reason for this trend can be explained by the difference in intermolecular force rather than intramolecular interaction, mainly related to the amount and strength of π···π and C—I···π interactions in different compounds. This work investigates the effect of host‐guest interaction on NLO, representing a new perspective for designing optical limiting materials. [ABSTRACT FROM AUTHOR]

Molecularly‐modified electrode materials that maintain stability over a broad pH range are rare. Typically, each electrochemical transformation necessitates a specifically tuned system to achieve strong binding and high activity of the catalyst. Here, we report the functionalisation of mesoporous indium tin oxide (mITO) electrodes with the macrocyclic host molecule pillar[6]arene (PA[6]). These electrodes are stable within the pH range of 2.4–10.8 and can be equipped with electrochemically active ruthenium complexes through host–guest interactions to perform various oxidation reactions. Benzyl alcohol oxidation serves as a model reaction in acidic media, while ammonia oxidation is conducted to assess the systems performance under basic conditions. PA[6]‐modified electrodes demonstrate catalytic activity for both reactions when complexed to different guest molecules and can be reused by reabsorption of the catalyst after its degradation. Furthermore, the system can be employed to perform subsequent reactions in electrolyte with varying pH, enabling the same electrode to be utilised in multiple different electrocatalytic reactions. [ABSTRACT FROM AUTHOR]

The synthesis and guest recognition properties of a neutral Pd24‐cubic cage, [{Pd3(NiPr)3PO}8(μ2‐Cl)24] 1 are reported. The formation of the cubical assembly takes place by an exclusive one‐pot ligand‐assisted pathway directed by an oximido linker. The initial coordination of the oximido ligand pre‐organizes the [Pd3(NiPr)3PO]3+ polyhedral building units into a tetrameric intermediate, which then transforms into an oximido‐tethered tetrahedral assembly and to the cubical cage 1 in the presence of chloride ions. In the absence of the directing oximido linker, no cage formation was observed, and the Pd6‐precursor was found to undergo self‐condensation, giving rise to a new pentameric polyhedral cluster, [Pd5{(NiPr)3PO}2(OAc)2(OH)2] 2. The central cavity of the cube has been probed for guest encapsulation studies, which shows a high binding with phenolic guest molecules with association constants of the order of 104–105 M−1. The favorable formation of host–guest complexes was attributed to the strong hydrogen bonding interactions between the host and guest functional groups. [ABSTRACT FROM AUTHOR]

Based on DFT calculations (ωB97XD/def2‐SVP/SVPfit), the ability and mechanism of noble gas encapsulation by series of cryptophanes were investigated. The focus was set to study the influence of different functionalization groups placed at the “gates” of cryptophanes cavity entrance by which the energy criteria were chosen as a main indicator for selective encapsulation of noble gases. Chosen functionalization groups were CH3, OCH3, OH, NH2, and Cl, and the encapsulation process of these cryptophanes was compared to a cryptophane without any functionalization group on its outer rim. Those groups were selected based on their different chemical properties and based on their size which will subsequently put additional steric restrictions on the cavity entrance. Chosen functionalization groups, beside their steric influence on the energy barrier magnitude, influence also the gating process through its chemical nature by which they can put an additional stabilization on noble gases encapsulation transition states enhancing the encapsulation process. Objective of this study was clearly to get better insights on the influence of those functional groups on the whole encapsulation process of noble gases. Large‐size noble gases (Xe and Rn) from all noble gases are best accommodated in the cavities of selected cryptophanes, on the other hand these noble gases require to pass the highest energy barrier through the gating process. From the series of investigated cryptophanes, the cryptophane with the OCH3 functionalization group has been identified as the one with the best capabilities to host investigated noble gases, but on the other side this cryptophane puts the highest energy criteria required for the previous gating process. [ABSTRACT FROM AUTHOR]

[1.1][n]Paracyclophanes ([1.1][n]PCPs) (3) with n=2, 3, and 4, which consist of two [n]paraphenylene units connected by methylene bridges, were synthesized using short synthetic pathways with good overall yields. Single‐crystal X‐ray diffraction analyses reveal that the paraphenylene unit in 3 is bent, resulting in an elliptic core structure of 3. The facing bridgehead carbons of the paraphenylene units are separated by a distance much shorter than the sum of the van der Waals radii of sp2‐carbon atoms. UV‐vis absorption spectra, fluorescence spectra, electrochemical measurements, and theoretical calculations were used to demonstrate the presence of through‐space (TS) conjugation in 3. Furthermore, host‐guest complex formation between 3D (n=3) and tetracyanoquinodimethane in the solid state was revealed. [ABSTRACT FROM AUTHOR]

The synthesis of molecular host–guest complexes with enhanced performance, relative to those of their components, is a central theme in supramolecular chemistry. Here we explore a host‐guest system consisting of an atomically precise gold nanocluster bound inside a zinc porphyrin nanoring. UV/Vis absorption and fluorescence titrations with different sized nanorings revealed strong binding between a pyridinethiol‐coated Au25 nanocluster and a nanoring consisting of six zinc porphyrin units, and complexation is confirmed by mass spectrometry. Formation of this assembly enhances the stability of the gold nanocluster. The host‐guest complex also exhibits remarkable activity and selectivity for photochemical CO2 to CO conversion and singlet oxygen generation. [ABSTRACT FROM AUTHOR]

Immobilizing molecular catalysts on electro‐conductive supports (for example, multi‐walled carbon nanotubes, CNTs) represent a promising way to well‐defined catalyst/support interfaces, which has shown appreciable performance for catalytic transformation. However, their full potential is far from achieved due to insufficient utilization of the intrinsic activity for each immobilized molecular catalyst, especially at loadings that should allow decent current densities. In the present work, we discover host–guest interaction between tetra‐crown ether substituted cobalt phthalocyanine and metal ions, for example K+ ions, not only eliminate catalyst aggregation at immobilization procedures but also reinforce catalyst/support interactions by additional electrostatic attractions under operational conditions. Through simple dip‐coating procedures, a successful single molecular dispersion is achieved. Such a catalyst/electrode interface is stable and can selectively catalyze CO2‐to‐CO conversion with Faradaic efficiency over 96%. Importantly, this interface maintains an almost unchanged turnover frequency (TOF) across all loading conditions, implying a full utilization of the intrinsic activity of supported molecular catalysts. Therefore, a simultaneous achievement of high TOF and high current density (TOF of 111 s−1 at 38 mA cm−2) is achieved, in an aqueous H‐type electrolyzer at an overpotential of 570 mV. [ABSTRACT FROM AUTHOR]

A new naphthalene diimides extended‐pillar[6]arene 1 with a large cavity and rich host‐guest complexation properties was synthesized in high yield. It can not only form 1 : 2 complexes with large size polycyclic aromatic hydrocarbons but also form 1 : 1 : 1 ternary complex with perylene and 2,7‐diazapyrenium. Moreover, the supramolecular exchange reaction from a 1 : 2 host‐guest complex 1 ⋅ (G3)2 formed by 1 and perylene to a 1 : 1 : 1 ternary complex 1 ⋅ G3 ⋅ G5 formed by 1 with perylene and 2,7‐diazapyrenium salt was also investigated by 1H NMR experiments as well as theoretically calculations. [ABSTRACT FROM AUTHOR]

Achieving high enantioselectivity with synthetic receptors, particularly in water, remains a significant challenge despite the success seen in natural biological systems. In this study, we introduce a facile synthesis of Tröger's base (TB)‐containing macrocyclic arenes (TBn), where TB units are linked via methylene bridges, providing the macrocycles with a rigid framework. Oxidation of enantiopure TBn yields corresponding chiral nitrogen oxides (TBnNO) with excellent water solubility, attributed to the high polarity of the N−O bond, surpassing the pH limitations of traditional ion‐functionalized approaches. Remarkably, TBnNO exhibits exceptional enantioselective recognition toward a wide range of chiral guests in aqueous solution, achieving enantioselectivities as high as 41.0. The underlying mechanism involves a combination of hydrophobic interactions and steric effects caused by rigid chiral cavities. These findings highlight the potential of nitrogen‐oxidized macrocycles as a transformative tool for supramolecular application in water. [ABSTRACT FROM AUTHOR]

Cucurbit[n]urils (CB[n]s) are cyclic macrocycles with rich host‐guest chemistry. In many cases, guest binding in CB[n]s results in host structural deformations. Unfortunately, measuring such deformations remains a major challenge, with only a handful of manual estimations reported in the literature. To address this challenge, we have developed the public program ElliptiCB[n], which is available on GitHub, that provides a robust and automated method for measuring the elliptical deformations in CB[n] hosts. We outline the development and validation of this approach, apply ElliptiCB[n] to measure the ellipticity of the 1113 available CB[n] structures from the Cambridge Structural Database (CSD), and directly investigate the structural deformations of CB[5], CB[6], CB[7], CB[8], and CB[10] hosts. We also report the general landscape of accessible CB[n] elliptical deformations and compare ellipticity distributions across CB[n] hosts and host‐guest complexes. We found that in almost all cases guest binding significantly impacts the distribution of host ellipticity distributions and that these distributions are dissimilar across host‐guest complexes of differently sized CB[n]s. We anticipate that this work will provide a useful approach for understanding of the flexibility of CB[n] hosts and will also enable future measurement and standardization of ellipticity measurements of CB[n]s. [ABSTRACT FROM AUTHOR]

Styrene-butadiene rubber (SBR) is an indispensable material in modern society, and the necessity for enhanced mechanical properties in SBR persists, particularly to withstand the rigors of challenging environmental conditions. To surmount the limitations of conventional cross-linking modes, mechanical bonds stabilized by host-guest recognition are incorporated as the cross-linking points of SBR to form mechanically interlocked networks (MINs). Compared with covalently cross-linked network, the representative MIN exhibits superior mechanical performance in terms of elongation (1392%) and breaking strength (4.6 MPa), whose toughness has surged by 17 times. Dissociation of host-guest recognition and subsequent sliding motion provide an effective energy dissipation mechanism, and the release of hidden length is also beneficial to enhance toughness. Furthermore, the introduction of the rotaxane cross-links made the network more pliable and possess damping and elastic properties, which can return to initial state with one minute rest interval. We aspire that this direct introduction method can serve as a blueprint, offering valuable insights for the enhancement of mechanical properties in conventional commercial polymer materials. [ABSTRACT FROM AUTHOR]

Noncovalent interactions (NCIs) are crucial for the formation and stability of host‐guest complexes, which have wide‐ranging implications across various fields, including biology, chemistry, materials science, pharmaceuticals, and environmental science. However, since NCIs are relatively weak and sensitive to bulk perturbation, direct and accurate measurement of their absolute strength has always been a significant challenge. This concept article aims to demonstrate the gas‐phase electrospray ionization (ESI)‐negative ion photoelectron spectroscopy (NIPES) as a direct and precise technique to measure the absolute interaction strength, probe nature of NCIs, and reveal the electronic structural information for host‐guest complexes. Our recent studies in investigating various host‐guest complexes that involve various types of NCIs such as anion–π, (di)hydrogen bonding, charge‐separated ionic interactions, are overviewed. Finally, a summary and outlook are provided for this field. [ABSTRACT FROM AUTHOR]

Dynamic hydrogel crosslinking captures network reorganization and self‐healing of natural materials, yet is often accompanied by reduced mechanical properties compared to covalent analogs. Toughening is possible in certain materials with processing by directional freeze‐casting and salting‐out, producing hierarchically organized networks with directionally enhanced mechanical properties. The implications of including dynamic supramolecular crosslinking alongside such processes are unclear. Here, a supramolecular hydrogel prepared from homoternary crosslinking by pendant guests with a free macrocycle is subsequently processed by directional freeze‐casting and salting‐out. The resulting hydrogels tolerate multiple cycles of compression. Excitingly, supramolecular affinity dictates the mechanical properties of the bulk hydrogels, with higher affinity interactions producing materials with higher Young's modulus and enhanced toughness under compression. The importance of supramolecular crosslinking is emphasized with a supramolecular complex that is converted in situ into a covalent crosslink. While supramolecular hydrogels do not fracture and spontaneously self‐heal when cut, their covalent analogs fracture under moderate strain and do not self‐heal. This work shows a molecular‐scale origin of bulk hydrogel toughening attributed to affinity and dynamics of supramolecular crosslinking, offering synergy in combination with bulk post‐processing techniques to yield materials with enhanced mechanical properties tunable at the molecular scale for the needs of specific applications. [ABSTRACT FROM AUTHOR]

This study explores the synthesis, structural characterization, and host‐guest interactions of heteroatom bridged nanobelts, focusing on a cyclothianthrene nanobelt and a fused nanobelt incorporating thianthrene and phenoxathiin. Utilizing a cyclization‐followed‐by‐bridging synthetic approach, both molecular belts were successfully synthesized, and their structures confirmed through NMR and MALDI‐TOF‐MS analysis. Crystallographic studies revealed that the cyclothianthrene nanobelt adopts an octagonal column‐like conformation, while the hybrid belt forms an oval tub‐shaped shape, both exhibiting distinct assembly motifs. The host‐guest chemistry of these nanobelts was investigated with fullerenes (C60, C70, and PC61BM). The cyclothianthrene belt showed no interaction with these fullerenes, whereas the other belt demonstrated adaptive binding capabilities, forming stable complexes with C60 and C70 through π–π interactions and C−H⋅⋅⋅S hydrogen bonds. The binding constants indicated that the hybrid belt has a stronger affinity for C70 due to better size complementarity. Additionally, its interaction with PC61BM showcased a specific 1 : 1 binding mode despite exhibiting a smaller binding constant. This study underscores the impact of heteroatom incorporation on the structural and functional properties of nanobelts, offering insights for future molecular design strategies. [ABSTRACT FROM AUTHOR]

A series of metal–organic cages featuring two stereogenic elements, in terms of the twisting of amide moieties within the ligand backbones and the rotation of diazaanthracene segments along the ligand ridges, were exploited. These two chiral components are correlative and serve as relays for transmitting chirality information between the internal and external cages. The chirality information induced by a chiral guest inside the cage cavity can pass through the cage framework and influence the orientation of the diazaanthracene segments on the periphery of the cage. In turn, the chirality of a stereogenic center within the diazaanthracene segments can transfer back into the cavity, enabling discrimination of enantiomeric guests. [ABSTRACT FROM AUTHOR]

A new antibacterial system (HG) based on the host–guest chemistry between pillar[5]arene and a zwitterionic guest was fabricated. The HG complex displayed excellent antibacterial and biofilm formation inhibition and dispersal activities against E. coli, S. aureus and MRSA. [ABSTRACT FROM AUTHOR]

Polyamines are essential analytes due to their critical role in various biological processes and human health in general. Due to their role as regulators for cell growth and proliferation (putrescine and spermine), as neuroprotectors, gero‐, and cardiovascular protectors (spermidine), and as bacterial growth indicators (cadaverine), rapid, simple, and cost‐effective methods for polyamine detection in biofluids are in demand. The present study focuses on the development and investigation of self‐assembled and fluorescent host⋅dye chemo‐sensors based on sulfonated pillar[5]arene for the specific detection of polyamines. Binding studies, as well as stability and functionality assessments of the turn‐on chemosensors for selective polyamine detection in saline and biologically relevant media, are shown. Furthermore, the practical applicability of the developed chemo‐sensors is demonstrated in biofluids such as human urine and saliva. [ABSTRACT FROM AUTHOR]

New stimulus‐responsive scaffolds are of interest as constituents of hierarchical supramolecular ensembles. 1,3,5–2,4,6‐Functionalized, facially segregated benzene moieties have a time‐honored role as building blocks for host molecules. However, their user as switchable motifs in the construction of multi‐component supramolecular structures remains poorly explored. Here, we report a molecular cage 1, which consists of a bent anthracene dimer 3 paired with 1,3,5‐tris(aminomethyl)‐2,4,6‐triethylbenzene 2. As the result of the pH‐induced ababab↔bababa isomerization of the constituent‐functionalized benzene units derived from 2, this cage can reversibly convert between an open state and a closed form, both in solution and in the solid state. Cage 1 was used to create stimuli‐responsive hierarchical superstructures, namely Russian doll‐like complexes with [K⊂18‐crown‐6⊂1]+ and [K⊂cryptand‐222⊂1]+. The reversible assembly and disassembly of these superstructures could be induced by switching cage 1 from its open to closed form. The present study thus provides an unusual example where pH‐triggered conformation motion within a cage‐like scaffold is used to control the formation and disassociation of hierarchical ensembles. [ABSTRACT FROM AUTHOR]

The cycling performance of zinc‐ion batteries is greatly affected by dendrite formation and side reactions on zinc anode, particularly in scenarios involving high depth of discharge (DOD) and low negative/positive capacity (N/P) ratios in full cells. Herein, drawing upon principles of host–guest interaction chemistry, we investigate the impact of molecular structure of electrolyte additives, specifically the −COOH and −OH groups, on the zinc negative electrode through molecular design. Our findings reveal that molecules containing these groups exhibit strong adsorption onto zinc anode surfaces and chelate with Zn2+, forming a H2O‐poor inner Helmholtz plane. This effectively suppresses side reactions and promotes dendrite‐free zinc deposition of exposed (002) facets, enhancing stability and reversibility of an average coulombic efficiency of 99.89 % with the introduction of Lactobionic acid (LA) additive. Under harsh conditions of 92 % DOD, Zn//Zn cells exhibit stable cycling at challenging current densities of 15 mA ⋅ cm−2. Even at a low N/P ratio of 1.3, Zn//NH4V4O10 full cells with LA electrolyte exhibit high‐capacity retention of 73 % after 300 cycles, significantly surpassing that of the blank electrolyte. Moreover, in a conversion type Zn//Br static battery with a high areal capacity (~5 mAh ⋅ cm−2), LA electrolyte sustains an improved cycling stability of 700 cycles. [ABSTRACT FROM AUTHOR]

Herein, we designed a chiral, axially‐twisted molecular scaffold (ATMS) using pyridine‐2,6‐dicarboxamide (PDC) unit as pivot, chiral trans‐cyclohexanediamine (CHDA) residues as linkers, and pyrene residues as fluorescent reporters. R,R‐ATMS exclusively adopted M‐helicity and produced differential response in UV‐vis, fluorescence, and NMR upon addition of tartaric acid (TA) stereoisomers allowing naked‐eye detection and enantiomeric content determination. Circular dichroism (CD) profile of R,R‐ATMS underwent unique changes during titration with TA stereoisomers ‐ while loss of CD signal at 345 nm was observed with equimolar D‐TA and meso‐TA, inversion was seen with equimolar L‐TA. Temperature increase weakened these interactions to partially recover the original CD signature of R,R‐ATMS. 2D NMR studies also indicated the significant structural changes in R,R‐ATMS in the solution state upon addition of L‐TA. Single crystal X‐ray diffraction (SCXRD) studies on the crystals of the R,R‐ATMS⊃D‐TA salt revealed the interacting partners stacked in arrays and ATMS molecules stabilized by π‐π stacking between its PDC and pyrene residues. Contrastingly, tightly‐packed supramolecular cages comprised of four molecules each of R,R‐ATMS and L‐TA were seen in R,R‐ATMS⊃L‐TA salt, and the ATMS molecules contorted to achieve CH‐π interactions between its pyrene residues. These results may have implications in modulating the helicity of topologically‐similar larger biomolecules. [ABSTRACT FROM AUTHOR]

The dynamic behaviour of metal‐ligand bonding cultivates stimuli‐mediated structural transformations in self‐assembled molecular architectures. The propensity of synthetically designed self‐assembled systems to interchange between higher‐order architectures is increased multi‐fold when the building blocks have higher conformational degrees of freedom. Herein, we report a new ligand, (2,7‐bis(di(pyridin‐4‐yl)amino)‐9H‐fluoren‐9‐one) (L), which, upon self‐assembly with a cis‐[(ethylene‐1,2‐diamine)Pd(NO3)2] acceptor (M), resulted in the formation of a M6L3 trifacial barrel (C1) in water. Interestingly, during crystallization, a rare M12L6 triangular orthobicupola architecture (C2) was generated along with C1. C2 could also be generated in solution via the application of several stimuli. C1 in aqueous media could stabilize one trans‐stilbene (tS) or cis‐stilbene (cS) molecule in its cavity, with a selectivity for the former from their mixture. Moreover, C1 acted as an effective host to prevent the otherwise facile photoisomerization of tS to cS inside its hydrophobic cavity under UV irradiation. Conversely, the visible‐light‐induced reverse isomerization of encapsulated cS to encapsulated tS could be achieved readily due to the better stabilization of tS within the cavity of C1 and its transparency to visible light. A multi‐functional system was therefore designed, which at the same time is stimuli‐responsive, shows isomer selectivity, and photo‐protects trans‐stilbene. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: 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 well illustrates the chemical and structural versatility of dihydrophenazine in the synthesis of macrocycles and their host‐guest chemistry. [ABSTRACT FROM AUTHOR]

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 of β-cyclodextrin (β-CD), a widely used host molecule, in the host-guest chemistry by magnetic anisotropy. A rigid and chiral lanthanide binding tag was attached to the β-CD to amplify the changes of nuclear magnetic resonance (NMR) signals in the host-guest recognition process. The installation of the paramagnetic lanthanide ion in β-CD greatly enhances the enantiomeric discrimination up to 30-fold in comparison with the diamagnetic β-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 of β-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. [ABSTRACT FROM AUTHOR]

Flexible poly-Lewis acids (PLA) based on the tribenzotriquinacene (TBTQ) scaffold have been synthesised. Hydrosilylation of 4b,8b,12b-triallyltribenzotriquinacene and subsequent exchange of the chlorine substituents with weaker coordinating triflate groups afforded a novel triple silyl-functionalised PLA. By regioselective hydroboration of triallyl–TBTQ with various organoboranes, PLAs with different Lewis acidities were obtained. The synthesised PLAs were combined with neutral bases in host–guest experiments. DOSY NMR spectroscopy was performed to elucidate the complexation process in solution. These experiments revealed a highly dynamic interaction between the boron-functionalised PLA and triazine. However, the addition of one equivalent of tris(dimethylphosphino(methyl))phenylsilane led to the formation of a 1 : 1 adduct, which was confirmed by diffusion experiments. [ABSTRACT FROM AUTHOR]

Although helicenes are promising molecules, the synthetic difficulty and tediousness have often been problems, and only small amounts of optically pure helicenes have been obtained by using chiral HPLC in most cases. Herein, aza[7]helicenes or closed‐aza[7]helicenes with (1R)‐menthyl substituents were selectively synthesized via the intramolecular Scholl reaction, and the diastereomeric pairs were separated by silica gel column chromatography. The optically pure helicenes were further transformed into the corresponding cyclic dimers, and the chiroptical properties were investigated. The rigid π‐frameworks of the dimers led to the high molar extinction coefficients and fluorescence quantum yields, while the twisted helicene moieties induced clear Cotton effects and CPL in the visible region, and the high CPL brightness (BCPL) was achieved. Furthermore, the cyclic dimers were found to have the macrocyclic cavity with the two NH groups suitable for the selective binding of a fluoride anion, which induced significantly redshifted fluorescence and CPL in the red region. [ABSTRACT FROM AUTHOR]

This study investigates unexpected competitive host–guest interactions of β‐cyclodextrin (β‐CD), which can occur with polymers in aqueous solution, using the examples of the two polymers poly(oligo(ethylene glycol) methyl ether methacrylate) and poly(glycerol mono methacrylate). Systematic structural modifications of the polymer provide insight into the host–guest interaction with β‐CD and the competition between side chains and end groups such as hydrophobic end groups remaining from reversible addition fragmentation chain transfer polymerization or intentionally implemented molecular recognition units such as arylazopyrazole photoswitches. [ABSTRACT FROM AUTHOR]

Chalice‐shaped tridentate poly‐Lewis acids (PLA) based on the tribenzotriquinacene (TBTQ) scaffold have been synthesised. Stannylation of the alkyne units, attached via phenyl‐spacers to the benzhydrylic positions to the TBTQ scaffold, with Me2NSnMe3 afforded the trimethyltin substituted TBTQ derivative. Replacement of these tin functions with other elements resulted in rigid boron‐ and aluminium‐functionalised PLAs. More flexible PLAs were obtained by hydrometallation reactions of the terminal alkyne groups of 4b,8b,12b‐tris((ethynyl)phenyl)tribenzotriquinacene. The resulting poly‐Lewis acids were tested for their acceptor abilities in host‐guest experiments with suitable bases. Preliminary tests with pyridine led to the synthesis of a large tridentate base with three pyridyl groups attached to a TBTQ backbone. Complexation of this Lewis base with the PLAs resulted in the formation of aggregates, which were studied in solution in more detail by 1H DOSY NMR experiments regarding their size. Further experiments were performed with the tridentate bases 1,4,7‐trimethyl‐1,4,7‐triazacyclononane and tris((dimethylphosphino)methyl)phenylsilane. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL), as an important chiroptical phenomenon, can not only directly characterize excited-state structural information about chiroptical materials but also has great application prospects in 3D optical displays, information storage, biological probes, CPL lasers and so forth. Recently, chiral organic small molecules with CPL have attracted a lot of research interest because of their excellent luminescence efficiency, clear molecular structures, unique flexibility and easy functionalization. Planar chiral organic compounds make up an important class of chiral organic small molecular materials and often have rigid macrocyclic skeletons, which have important research value in the field of chiral supramolecular chemistry (e.g., chiral self-assembly and chiral host–guest chemistry). Therefore, research into planar chiral organic compounds has become a hotspot for CPL. It is time to summarize the recent developments in CPL-active compounds based on planar chirality. In this feature article, we summarize various types of CPL-active compounds based on planar chirality. Meanwhile, we overview recent research in the field of planar chiral CPL-active compounds in terms of optoelectronic devices, asymmetric catalysis, and chiroptical sensing. Finally, we discuss their future research prospects in the field of CPL-active materials. We hope that this review will be helpful to research work related to planar chiral luminescent materials and promote the development of chiral macrocyclic chemistry. [ABSTRACT FROM AUTHOR]

Biomembranes function as hydrophobic barriers for hydrophilic substances enabling compartmentalization in biological systems. This poses, however, a problem for the targeted introduction of cargo into cells. The result is a high demand for delivery pathways into cells with the goal to investigate biological processes or to treat diseases by improved delivery. Polycationic cell‐penetrating peptides (CPPs) are interesting as they can cross cell membranes and transport attached cargos directly into the cytosol. Their efficiency can be improved by anionic amphiphilic counterion activators, which bind to the CPPs to form charge‐neutralized counterion‐CPP complexes with sufficient hydrophobicity to cross the lipid bilayer membrane. This review summarizes recent results, which establish amphiphilic calixarenes as a new class of biocompatible and non‐cytotoxic counterion activators with very high transport activities at nanomolar concentrations. We also include a brief summary of fluorescence‐based assays with large unilamellar vesicles (LUVs) to investigate counterion‐activated transport. Current methods use liposome‐encapsulated, supramolecular host‐dye reporter pairs including calixarenes, which provide new mechanistic insights and enable rapid in vitro identification of suitable activators. Taken together, amphiphilic calixarenes are currently emerging as prime candidates for counterion activation of membrane transport, which are highly modifiable and can be specifically tailored towards different cargoes and membrane types. [ABSTRACT FROM AUTHOR]

The carbon nanorings, possessing a radial π system, have garnered significant attention primarily due to their size‐dependent photophysical properties and the presence of a unique curved π‐conjugated cavity. This is evidenced by the rapid proliferation of publications. Furthermore, the integration of building blocks into CPP skeletons can confer [n]CPPs with novel and exceptional photophysical and electronic characteristics, as well as chiral properties and host‐guest interactions, thereby augmenting the diversity of [n]CPPs. Notably, the curved π surface structures and concave cavity of carbon nanorings enable them to host aromatic or non‐aromatic guests with a complementarily curved surface, resulting in interesting binary or ternary complexes. This review provides a comprehensive treatment of literature reports on binary and ternary complexes, focusing on both their host‐guest interactions and properties. It is important to note that the scope of this review is limited to host‐guest chemistry in binary and ternary complexes based on π‐conjugated carbon nanorings. [ABSTRACT FROM AUTHOR]

We theoretically investigated the host–guest chemistry between belt-like cycloparaphenylenes (CPPs) and entrapped bowl-shaped sumanene and corannulene. Density functional theory calculations show that the buckybowls can be stabilized in a CPP host with an appropriately sized cavity (e.g., [10]CPP) through multi-site CH–π interactions. Arising from the confined intermolecular interactions within the cavity, the restrictive buckybowls display novel reactivity distinct from that in their free state. [ABSTRACT FROM AUTHOR]

Click chemistry has reached its maturity as the weapon of choice for the irreversible ligation of molecular fragments, with over 20 years of research resulting in the development or improvement of highly efficient kinetically controlled conjugation reactions. Nevertheless, traditional click reactions can be disadvantageous not only in terms of efficiency (side products, slow kinetics, air/water tolerance, etc.), but also because they completely avoid the possibility to reversibly produce and control bound/unbound states. Recently, non‐covalent click chemistry has appeared as a more efficient alternative, in particular by using host‐guest self‐assembled systems of high thermodynamic stability and kinetic lability. This review discusses the implementation of molecular switches in the development of such non‐covalent ligation processes, resulting in what we have termed stimuli‐responsive click chemistry, in which the bound/unbound constitutional states of the system can be favored by external stimulation, in particular using host‐guest complexes. As we exemplify with handpicked selected examples, these supramolecular systems are well suited for the development of human‐controlled molecular conjugation, by coupling thermodynamically regulated processes with appropriate temporally resolved extrinsic control mechanisms, thus mimicking nature and advancing our efforts to develop a more function‐oriented chemical synthesis. [ABSTRACT FROM AUTHOR]

Among mechanically interlocked supramolecular systems with cyclodextrins (CDs), successful examples of CD‐based catenanes are limited compared to a number of CD rotaxanes owing to the synthetic difficulties. We herein demonstrate an efficient synthesis of a CD‐based catenane using a meso‐arylporphyrin (Por) platform. Using Por modified with two olefin‐terminated oxyethylene chains at the cis‐meso‐positions, an interlocked Por‐CD catenane was synthesized via olefin metathesis in the presence of per‐O‐methylated β‐CD (TMe‐β‐CD) in water. The novel Por‐CD catenane was obtained in 30 % isolated yield, which was characterized by MALDI‐TOF mass and NMR spectroscopies. In the latter part, we demonstrate determination of the binding constants between TMe‐β‐CD and meso‐(4‐sulfonatophenyl)porphyrin using Por‐CD catenane, 2,6‐di‐O‐methyl‐β‐CD (DMe‐β‐CD), and 13C‐labeled TMe‐β‐CD (13C‐TMe‐β‐CD). The host‐guest exchange reaction from the Por‐CD catenane/DMe‐β‐CD to the Por‐CD catenane/TMe‐β‐CD complexes was directly monitored through 1D HMQC spectroscopy. The ratio of these complexes revealed the difference in the binding affinities of DMe‐β‐CD and TMe‐β‐CD to Por. The stable 1 : 2 inclusion complex between meso‐tetrakis(4‐sulfonatophenyl)porphyrin (TPPS) and TMe‐β‐CD has been well‐studied for many years. This study is the first to determine the respective binding constants, K1 and K2, using the model system, to be 3.0×107 M−1 and 3.4×107 M−1, respectively. [ABSTRACT FROM AUTHOR]

Controlling supramolecular systems between different functional forms by utilizing acids/bases as stimuli is a formidable challenge, especially where labile coordination bonds are involved. A pair of acid/base responsive, interconvertible 1,5‐enedione/pyrylium based Pd2L4‐type cages are prepared that exhibit differential guest binding abilities towards disulfonates of varied sizes. A three‐state switch has been achieved, where (i) a weakly coordinating base induced cage‐to‐cage transformation in the first step, (ii) a strongly coordinating base triggered cage disassembly as the second step, and (iii) the third step shows acid(strong) promoted generation of initial cage, thereby completing the cycle. To our surprise, binding of a specific disulfonate guest facilitated cage‐to‐cage transformations by inducing strain on the cage assembly thereby opening the labile pyrylium rings of the cage. Through a competitive guest binding study, we demonstrated the superior guest binding capability of the octacationic pyrylium‐based cage over a similar‐sized tetracationic cage. These results provide a reliable approach to reversibly modulate the guest binding properties of acid/base‐responsive self‐assembled coordination cages. [ABSTRACT FROM AUTHOR]

The interactions between ether naphthotube and a series of dication guests in organic solution were investigated. It was found that ether naphthotube formed stable host‐guest complexes selectively with these guests in a 1 : 1 stoichiometric ratio with association constants ranging from 102 to 106 M−1, which were confirmed by 1H‐NMR spectra and ITC experiments. The host‐guest interactions are driven by enthalpy change as the entropic factors are unfavorable. Positive correlations between ΔH and ΔS have been observed in the host‐guest complexes. Furthermore, the para‐substitution of the guests can significantly affect the binding affinities through a combination of field/inductive and resonance effects by following a linear free energy relationship. Based on the host‐guest complexes composed of ether naphthotube and organic cations, two interlocked [2]rotaxanes were prepared by cationization reaction and Huisgen cycloaddition between the cations and the stopper components. The ether naphthotube‐based host‐guest complexes are useful for creating sophisticated interlocked molecules. [ABSTRACT FROM AUTHOR]

Over the past decades, supramolecular luminescent materials (SLMs) have attracted considerable attention due to their dynamic noncovalent interactions, versatile functions, and intriguing applications in many research fields. From construction to application, great efforts and progress have been made in color‐tunable SLMs in recent years. In order to realize multicolor luminescence, various design strategies have been proposed. Macrocyclic chemistry, one of the brightest jewels in the field of supramolecular chemistry, has played a crucial role in the construction of stimuli‐responsive and emission‐tunable SLMs. Moreover, the flexible and tunable conformation and multiple noncovalent complexation sites of the macrocyclic arenes (MAs) afford a new opportunity to create such dynamic smart luminescent materials. Inspired by our reported work on the color‐tunable supramolecular crystalline assemblies modulated by the conformation of naphth[4]arene, this Concept provides a summary of the latest developments in the construction of color‐tunable MA‐based SLMs, accompanied by the various construction strategies. The aim is to provide researchers with a new perspective to construct color‐tunable SLMs with fascinating functions. [ABSTRACT FROM AUTHOR]

Abstract We report the first synthesis of a water‐soluble [9]cycloparaphenylene derivative containing three hydrindacene (1,2,3,5,6,7‐hexahydro‐s‐indacene) units with four carboxylates at the 2,6‐positions via a macrocyclic gold complex. This crown‐shaped macrocyclic compound exhibits remarkable water solubility, of up to 16 mmol L−1 (2.6 g/100 mL), as well as strong visible fluorescence in water (λem=447 nm, ϕF=0.64, brightness (ϵ×ϕF)=5.1×104). This molecule effectively encapsulates cationic guest compounds, such as methyl viologen dichloride, as indicated by a change in visible fluorescence.

Macrocyclic arenes have gained considerable attention for their structural diversity and widespread applications. In this research, a new kind of macrocyclic arenes, namely prism[2]dihydrophenazines (anti‐P2P20, syn‐P2P20, and P2P22), composed of two dihydrophenazine derivatives subunits bridged by methylene groups, were conveniently synthesized by AlCl3‐catalyzed one‐pot condensation in 1,2‐dichloroethane. Both anti‐P2P20 and its isomer syn‐P2P20 exhibited flexible and convertible conformation with narrow cavity, while P2P22 possessed rigid and rhombic‐like skeleton due to the more steric hindrance on subunits. In addition, the selection of electron‐deficient guest was found to influence the outside binding behavior of syn‐P2P20. Fantastic regular supramolecular tessellation was fabricated by tiling of syn‐P2P20 with tetrafluoro‐1,4‐benzoquinone (TFB) through the exo‐wall interactions. Using 1,5‐difluoro‐2,4‐dinitrobenzene (DFN) as a linker, only the regular 2D network superstructure with periodic units in a plane was obtained through cocrystallization. This work not only reports the construction of supramolecular tessellations by using prism[2]dihydrophenazines as building blocks, but also provides a new perspective for the design of macrocyclic arenes and fabrication of 2D supramolecular materials. [ABSTRACT FROM AUTHOR]

Experimental realization of strong coupling between a single exciton and plasmons remains challenging as it requires deterministic positioning of the single exciton and alignment of its dipole moment with the plasmonic fields. This study aims to combine the host–guest chemistry approach with the cucurbit[7]uril-mediated active self-assembly to precisely integrate a single methylene blue molecule in an Au nanodimer at the deterministic position (gap center of the nanodimer) with the maximum electric field (EFmax) and perfectly align its transition dipole moment with the EFmax, yielding a large spectral Rabi splitting of 116 meV for a single-molecule exciton—matching the analytical model and numerical simulations. Statistical analysis of vibrational spectroscopy and dark-field scattering spectra confirm the realization of the single exciton strong coupling at room temperature. Our work may suggest an approach for achieving the strong coupling between a deterministic single exciton and plasmons, contributing to the development of room-temperature single-qubit quantum devices. Realising single molecule strong coupling with plasmons achieving both deterministic molecule positioning and dipole alignment with the mode field has proven challenging so far. Here, the authors fill this gap by placing a single molecular emitter in the gap centre of an Au nanodimer system. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluoroalkyl substances (PFAS) pose a rapidly increasing global problem as their widespread use and high stability lead worldwide to water contamination, with significant detrimental health effects.[1] Supramolecular chemistry has been invoked to develop materials geared towards the specific capture of PFAS from water,[2] to reduce the concentration below advisory safety limits (e.g. 70 ng/L for the sum of perfluorooctane sulfonic acid, PFOS and perfluorooctanoic acid, PFOA). Scale‐up and use in natural waters with high PFAS concentrations has hitherto posed a problem. Here we report a new type of host–guest interaction between deca‐ammonium‐functionalized pillar[5]arenes (DAF−P5s) and perfluoroalkyl acids. DAF−P5 complexes show an unprecedented 1 : 10 stoichiometry, as confirmed by isothermal calorimetry and X‐ray crystallographic studies, and high binding constants (up to 106 M−1) to various polyfluoroalkyl acids. In addition, non‐fluorinated acids do not hamper this process significantly. Immobilization of DAF−P5s allows a simple single‐time filtration of PFAS‐contaminated water to reduce the PFOS/PFOA concentration 106 times to 15–50 ng/L level. The effective and fast (<5 min) orthogonal binding to organic molecules without involvement of fluorinated supramolecular hosts, high breakthrough capacity (90 mg/g), and robust performance (>10 regeneration cycles without decrease in performance) set a new benchmark in PFAS‐absorbing materials. [ABSTRACT FROM AUTHOR]

The artificial microenvironments inside coordination cages have gained significant attention for performing enzyme‐like catalytic reactions by facilitating the formation of labile and complex molecules through a "ship‐in‐a‐bottle" approach. Despite many fascinating examples, this approach remains scarcely explored in the context of synthesizing metallic clusters such as polyoxometalates (POMs). The development of innovative approaches to control and influence the speciation of POMs in aqueous solutions would greatly advance their applicability and could ultimately lead to the formation of elusive clusters that cannot be synthesized by using traditional methods. In this study, we employ host–guest stabilization within a coordination cage to enable a novel cavity‐directed synthesis of labile POMs in aqueous solutions under mild conditions. The elusive Lindqvist [M6O19]2− (M=Mo or W) POMs were successfully synthesized at room temperature via the condensation of molybdate or tungstate building blocks within the confined cavity of a robust and water‐soluble Pt6L4(NO3)12 coordination cage. Importantly, the encapsulation of these POMs enhances their stability in water, rendering them efficient catalysts for environmentally friendly and selective sulfoxidation reactions using H2O2 as a green oxidant in a pure aqueous medium. The approach developed in this paper offers a means to synthesize and stabilize the otherwise unstable metal‐oxo clusters in water, which can broaden the scope of their applications. [ABSTRACT FROM AUTHOR]

Crown ethers are cyclic polyethers of varied ring sizes. The ability to bind to cations of specific size and charge is based on the ring size, donor atoms present in the crown cavity, and geometry. The host-guest chemistry of crown ethers is further enriched by the introduction of other donor atoms into the crown cavity. For example, aza-crown ethers are crown ethers wherein one or more oxygen atoms are replaced by nitrogen donors. The replacement of donor atoms appreciably alters the ability of the crown cavity to host guest molecules. Phosphorus donors can be introduced to the crown ethers on the periphery to generate hybrid ligands. In these hybrid "CrownPhos" ligand systems, the crown cavity selectively binds to hard cations and phosphorus donors preferentially bind to soft transition metal centers. The presence of guest cations in the crown ether cavity can alter the steric and electronic properties of the phosphorus donors and thereby modulate catalytic ability. The current review focuses on various synthetic and catalytic aspects of crown ethers, aza-crown ethers, and thia-crown ethers appended with phosphorus donors on the periphery. Crownphos: Crown ethers decorated with tertiary phosphorus donors. The details of syntheses, reactivity, host-guest chemistry, and catalytic activities of functionalized crown ethers with phosphorus donors reported in the literature are discussed in the review. [ABSTRACT FROM AUTHOR]