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Control of Excited-State Supramolecular Assembly Leading to Halide Photorelease
摘要： Ground- and excited-state control of halide supramolecular assembly was achieved through the preparation of a series of ester- and amide-functionalized ruthenium polypyridyl complexes in CH2Cl2. Hydrogen-bonding amide and alcohol groups on the receptor ligand were found to direct interactions with halide, while halide association with the ethyl ester groups was not observed. The various functional groups on the receptor ligands tuned the ground-state equilibrium constants over 2 orders of magnitude (1 × 10^5 to 1 × 10^7 M^?1), and the fractional contribution of each hydrogen-bond donor to the total equilibrium constant was determined. Pulsed-laser excitation of the complexes resulted in excited-state localization on the ester- or amide-functionalized ligands. In the case where the excited state was oriented toward an associated halide ion (the amide complexes), an 80 ± 10 meV Coulombic repulsion was induced that lowered the excited-state equilibrium constant (K*_eq) and resulted in halide photorelease. The rate constants for excited-state halide release (k*_21) were determined, and the values varied based on the functional groups present in the receptor ligand. Complexes with more hydrogen-bonding donors had smaller rate constants for halide photorelease. In a complex without a specific receptor ligand, the excited-state dipole was not oriented toward the associated halide, and the excited state was therefore found to have a larger equilibrium constant for halide association than the ground state.
关键词： halide supramolecular assembly,excited-state equilibrium,photorelease,hydrogen-bonding,ruthenium polypyridyl complexes
更新于2025-11-19 16:56:35
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Smart Supramolecular “Trojan Horse”-Inspired Nanogels for Realizing Light-Triggered Nuclear Drug Influx in Drug-Resistant Cancer Cells
摘要： Efficient nuclear delivery of anticancer drugs evading drug efflux transporters (DETs) on the plasma and nuclear membranes of multidrug-resistant cancer cells is highly challenging. Here, smart nanogels are designed via a one-step self-assembly of three functional components including a biocompatible copolymer, a fluorescent organosilica nanodot, and a photodegradable near-infrared (NIR) dye indocyanine green (ICG). The rationally designed nanogels have high drug encapsulation efficiency (≈99%) for anticancer drug doxorubicin (Dox), self-traceability for bioimaging, proper size for passive tumor targeting, prolonged blood circulation time for enhanced drug accumulation in tumor, and photocontrolled disassemblability. Moreover, the Dox-loaded nanogels can effectively kill multidrug-resistant cells via two steps: 1) They behave like a “Trojan horse” to escape from the DETs on the plasma membrane for efficiently transporting the anticancer “soldier” (Dox) into the cytoplasm and preventing the drugs from being excreted from the cells; 2) Upon NIR light irradiation, the photodegradation of ICG leads to the disassembly of the nanogels to release massive Dox molecules, which can evade the DETs on the nuclear membrane to exert their intranuclear efficacy in multidrug-resistant cells. Combined with their excellent biocompatibility, the nanogels may provide an alternative solution for overcoming cancer multidrug resistance.
关键词： nuclear delivery,photocontrollable drug release,cancer theranostics,silicon-based nanomaterials,supramolecular assembly
更新于2025-09-23 15:22:29
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Building from Ga-porphyrins: Synthesis of Ga-Acetylide complexes using acetylenes and polyynes
摘要： Multidimensional, conjugated building blocks have been formed through the axial coordination of polyynes to the central Ga atom of tetraarylporphyrins. Electron deficient pentafluorophenyl substituents in the meso-positions provide more stable s-acetylide complexes to Ga than analogous structures with tert-butylphenyl groups. Mono-, di-, and triynes have been used, including a pyridyl endcapped diyne that allows for formation of porphyrin triads through coordination of the pyridyl ligand to a Ru porphyrin.
关键词： hierarchical assembly,Ga-porphyrin,polyyne,supramolecular assembly,axial s-acetylide
更新于2025-09-23 15:21:01
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Imaging Supramolecular Morphogenesis with Confocal Laser Scanning Microscopy at Elevated Temperatures
摘要： The morphogenesis of supramolecular assemblies is a highly dynamic process that has only recently been recognized, and our understanding of this phenomenon will require imaging techniques capable of crossing scales. Shape transformations depend both on the complex energy landscapes of supramolecular systems and the kinetically controlled pathways that define their structures and functions. We report here the use of confocal laser scanning microscopy coupled with a custom-designed variable-temperature sample stage that enables in situ observation of such shape changes. The submicrometer resolution of this technique allows for real-time observation of the nanostructures in the native liquid environments in which they transform with thermal energy. We use this technique to study the temperature-dependent morphogenic behavior of peptide amphiphile nanofibers and photocatalytic chromophore amphiphile nanoribbons. The variable-temperature confocal microscopy technique demonstrated in this work can sample a large volume and provides real-time information on thermally induced morphological changes in the solution.
关键词： in situ microscopy,confocal microscopy,nanofibers,nanoribbons,supramolecular assembly
更新于2025-09-23 15:21:01
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Reply to Comment on a??Photo-Controlled Reversible Microtubule Assembly Mediated by Paclitaxel-Modified Cyclodextrina??
摘要： In a Correspondence on our previous study “Photo-Controlled Reversible Microtubule Assembly Mediated by Paclitaxel-Modified Cyclodextrin” published in this journal in 2018,[1a] Thorn-Seshold comments on our results.[1b] First of all, we would like to appreciate his comments and interest in our work. The aggregation behavior of microtubules (MTs) in our work has been demonstrated from the viewpoint of macrocycle-based host–guest complexation at the supramolecular level and subsequently, the MT stabilizers based on azobenzene-modified paclitaxel (PTX) derivatives as photoswitchable small molecules have been investigated by Thorn-Seshold and co-workers in 2019.[2] In our case, the microscopy results showed that the MT morphology was dramatically affected by the photoisomeric complexation between cyclodextrin (CD) and arylazopyrazole (AAP). No fibrous assembly as free MT could be observed in the presence of free PTX-CD, PTX-AAP, or their inclusion complex in the cis/trans states. Therefore, the introduction of CD and AAP definitely influenced the self-assembling behavior between PTX and MT. Moreover, fluorescent-dye-staining assays demonstrated that the PTX-derived host and guest compounds still possessed MT-targeting ability to some extent, because MT could be co-labeled by FITC-tagged antibodies and adamantane-containing RhB. Thus, the microtubular aggregation was proposed as one of the possible assembling modes in Scheme 1 (cartoon presentation). The binding mode of MT with CD and AAP was directly deduced from our microscopy images and cellular confocal experiments. The biological effect in our work may be jointly attributed to both the PTX-dependent pathway (PTX-induced microtubular stabilization) and the PTX-independent pathway (complexation-induced multivalent supramolecular cross-linkage) at the nanometer scale.[3] Under these circumstances, one reasonable explanation is that the latter (independent) effect may become comparable to the former (dependent) one when the MT affinity is reduced by chemical modification at the 2’-OH position of PTX. Moreover, as a widely studied macrocyclic receptor in supramolecular chemistry, CD can form a diversity of supramolecular assemblies.[4] To determine the precise binding mode, in addition to the viewpoint of structural biology for evaluating the original PTX–MT interaction at the single-molecule level, many other factors and multiple supramolecular noncovalent interactions (e.g., self-inclusion, self-exclusion, amphiphilicity, extensive hydrogen bonding, and supramolecular multivalency/cooperativity) between PTX-CD and PTX-AAP should also be taken into account. For example, the multivalent inclusion complexation between multiple CD and PTX molecules may confer high stability to the nano-assembly.[5] Therefore, in our opinion, no binding mode can be exclusively confirmed at the present time until the hyperfine structures of such multicomponent CD–protein assemblies have been obtained both in solution and in the solid state (e.g., in a single crystal). Moreover, azobenzene/CD is one of the most frequently used host–guest pairs in adjusting the assembling/disassembling behavior of proteins and other biomacromolecules.[6] Meanwhile, AAP is a new type of azo compound, which possesses quite distinct photophysical behavior compared to conventional azobenzenes, such as enhanced photostability and photoconversion efficiency. The biological effect of pristine AAP on pure MT may deserve further attention, but this aspect was outside the scope of our previous study. Overall, based on NMR, TEM, UV/Vis transmittance, and confocal microscopy experiments, we clearly demonstrated in our previous study that 1) the MT self-assembling morphology can be strongly affected by the host–guest complexation between CD and AAP, and that 2) complexation-induced MT aggregation can be realized in a cellular environment. Thus, our work provides an alternative supramolecular chemistry method to modulate a biomacromolecular assembling process. Finally, we would like to thank Dr. Thorn-Seshold for his constructive suggestions and express our hope that we can improve the chemical simulation and gain further insight into the biological mechanism in further work.
关键词： molecular recognition,photo-responsiveness,cyclodextrin,supramolecular assembly,microtubules
更新于2025-09-23 15:19:57
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Reply to Comment on a??Photo-Controlled Reversible Microtubule Assembly Mediated by Paclitaxel-Modified Cyclodextrina??
摘要： In a Correspondence on our previous study ?Photo-Controlled Reversible Microtubule Assembly Mediated by Paclitaxel-Modified Cyclodextrin“ published in this journal in 2018,[1a] Thorn-Seshold comments on our results.[1b] First of all, we would like to appreciate his comments and interest in our work. The aggregation behavior of microtubules (MTs) in our work has been demonstrated from the viewpoint of macrocycle-based host–guest complexation at the supramolecular level and subsequently, the MT stabilizers based on azobenzene-modified paclitaxel (PTX) derivatives as photoswitchable small molecules have been investigated by Thorn-Seshold and co-workers in 2019.[2] In our case, the microscopy results showed that the MT morphology was dramatically affected by the photoisomeric complexation between cyclodextrin (CD) and arylazopyrazole (AAP). No fibrous assembly as free MT could be observed in the presence of free PTX-CD, PTX-AAP, or their inclusion complex in the cis/trans states. Therefore, the introduction of CD and AAP definitely influenced the self-assembling behavior between PTX and MT. Moreover, fluorescent-dye-staining assays demonstrated that the PTX-derived host and guest compounds still possessed MT-targeting ability to some extent, because MT could be co-labeled by FITC-tagged antibodies and adamantane-containing RhB. Thus, the microtubular aggregation was proposed as one of the possible assembling modes in Scheme 1 (cartoon presentation). The binding mode of MT with CD and AAP was directly deduced from our microscopy images and cellular confocal experiments. The biological effect in our work may be jointly attributed to both the PTX-dependent pathway (PTX-induced microtubular stabilization) and the PTX-independent pathway (complexation-induced multivalent supramolecular cross-linkage) at the nanometer scale.[3] Under these circumstances, one reasonable explanation is that the latter (independent) effect may become comparable to the former (dependent) one when the MT affinity is reduced by chemical modification at the 2’-OH position of PTX.
关键词： molecular recognition,photo-responsiveness,cyclodextrin,supramolecular assembly,microtubules
更新于2025-09-23 15:19:57
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Guest Inclusion Modulates Concentration and Persistence of Photogenerated Radicals in Assembled Triphenylamine Macrocycles
摘要： Substituted triphenylamine (TPA) radical cations show great potential as oxidants and as spin containing units in polymer magnets. Their properties can be further tuned by supramolecular assembly. Here, we examine how the properties of photogenerated radical cations, intrinsic to TPA macrocycles, are altered upon their self-assembly into 1D columns. These macrocycles consist of two TPAs and two methylene ureas which drive the assembly into porous organic materials. Advantageously, upon activation the crystals can undergo guest exchange in a single-crystal-to-single-crystal transformation generating a series of isoskeletal host-guest complexes whose properties can be directly compared. Photoinduced electron transfer, initiated using 365 nm LED’s, affords radicals at room temperature as observed by EPR spectroscopy. The line shape of the EPR spectra and the quantity of radicals can be modulated by both polarity and heavy atom inclusion of the encapsulated guest. These photogenerated radicals are persistent, with half-lives between 1-7 days and display no degradation upon radical decay. Re-irradiation of the samples can restore the radical concentration back to a similar maximum concentration, a feature that is reproducible over several cycles. EPR simulations of a representative spectrum indicate two species, one containing two N hyperfine interactions and an additional broad signal with no resolvable hyperfine interaction. Intriguingly, TPA analogs without bromine substitution also exhibit similar quantities of photogenerated radicals, suggesting that supramolecular strategies can enable more flexibility in stable TPA radical structures. These studies will help guide the development of new photoactive materials.
关键词： photoinduced electron transfer,supramolecular assembly,radical cations,triphenylamine,EPR spectroscopy
更新于2025-09-12 10:27:22
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Step-growth polymerization of traptavidin-DNA conjugates for plasmonic nanostructures
摘要： Here, we use two important biomaterials, protein and DNA, to construct self-assembled nanostructures through Watson-Crick base-paring of DNAs. We apply a simple magnetic separation method to purify traptavidin-DNA conjugates, and demonstrate synthesis of linear arrays of traptavidin-DNA conjugates via the step-growth polymerization approach with pre-determined DNA sequences. Using the traptavidin-DNA array as a template, we assemble gold nanoparticles to form linear plasmonic nanostructures in a programmable manner. The traptavidin-DNA conjugates thus provide a convenient platform for one-dimensional assembly of biotinylated nanomaterials for many biomedical applications from drug delivery to bio-sensing.
关键词： Traptavidin,Plasmonic nanostructure,Supramolecular assembly,Protein-DNA conjugate,DNA nanostructure
更新于2025-09-12 10:27:22
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Building from Ga-porphyrins: Synthesis of Ga-Acetylide complexes using acetylenes and polyynes
摘要： Multidimensional, conjugated building blocks have been formed through the axial coordination of polyynes to the central Ga atom of tetraarylporphyrins. Electron deficient pentafluorophenyl substituents in the meso-positions provide more stable s-acetylide complexes to Ga than analogous structures with tert-butylphenyl groups. Mono-, di-, and triynes have been used, including a pyridyl endcapped diyne that allows for formation of porphyrin triads through coordination of the pyridyl ligand to a Ru porphyrin.
关键词： polyyne,axial s-acetylide,Ga-porphyrin,supramolecular assembly,hierarchical assembly
更新于2025-09-09 09:28:46
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Dual sites fluorescence probe for hydrogen sulfide: AIEE activity and supramolecular assembly with β-cyclodextrin
摘要： One aggregation-induced emission enhancement (AIEE) active compound based on α–cyanostilbenes and maleic anhydride group were synthesized. The “Turn-On” fluorescence recognition for H2S was evaluated both in aqueous solution and cells. It was found that cyanostilbenes group acts as the first reactive site and maleimide group acts as the second site to H2S. Supramolecular assembly with β-cyclodextrin successfully revealed the reaction mechanism of 3-state model.
关键词： α–cyanostilbenes,Hydrogen sulfide,Supramolecular assembly,Maleic anhydride,Aggregation–induced emission
更新于2025-09-09 09:28:46