Hydrogen-bonded Framework Research Articles

Construction of a hydrogen-bonded organic framework-based therapeutic platform by one-pot method.

The anticancer drug camptothecin (CPT) was successfully in situ loaded into a hydrogen-bonded organic framework (HOF) by one-pot method with a high loading efficiency of 42 wt%. The resultant HOF based therapeutic platform could suppress the tumor growth effectively.

H-bonded organic frameworks as ultrasound-programmable delivery platform.

The precise control of mechanochemical activation within deep tissues using non-invasive ultrasound holds profound implications for advancing our understanding of fundamental biomedical sciences and revolutionizing disease treatments1-4. However, a theory-guided mechanoresponsive materials system with well-defined ultrasound activation has yet to be explored5,6. Here we present the concept of using porous hydrogen-bonded organic frameworks (HOFs) as toolkits for focused ultrasound (FUS) programmably triggered drug activation to control specific cellular events in the deep brain, through on-demand scission of the supramolecular interactions. A theoretical model is developed to potentially visualize the mechanochemical scission and ultrasound mechanics, providing valuable guidelines for the rational design of mechanoresponsive materials to achieve programmable control. To demonstrate the practicality of this approach, we encapsulate the designer drug clozapine N-oxide (CNO) into the optimal HOF nanocrystals for FUS-gated release to activate engineered G-protein-coupled receptors in the ventral tegmental area (VTA) of mice and rats and hence achieve targeted neural circuit modulation even at depth 9 mm with a latency of seconds. This work demonstrates the capability of ultrasound to precisely control molecular interactions and develops ultrasound-programmable HOFs to non-invasively and spatiotemporally control cellular events, thereby facilitating the establishment of precise molecular therapeutic possibilities.

Synthesis of Porphyrin Derivatives Bearing Six Carboxylic Acids for the Formation of Three-Dimensional Hydrogen-Bonded Network Structures.

we synthesized a series of porphyrin derivatives with six carboxylic acid groups to explore their potential in forming hydrogen-bonded networks (YSHs). By systematically varying the position and structure of these carboxylic acid groups, we observed distinct types of hydrogen-bonded frameworks, including two- and three-dimensional networks. Using single-crystal X-ray crystallography, we confirmed that these derivatives form YSHs with unique structural properties influenced by carboxylic acid positioning and π-π interactions. The 1Zn derivative forms a robust 3D hydrogen-bonded network stabilized by π-π stacking interactions, while the 2Ni derivative, with no such stacking, exhibits reduced stability and collapses upon solvent removal. Structural variations like the terphenylene and biphenyl linkers in 3Zn and 4Zn lead to flexible frameworks, while the 5Zn dimer forms two distinct structures depending on the solvent environment. Our findings reveal that careful control over carboxylic acid orientation and linker structure enables the design of diverse hydrogen-bonded networks with tunable stability and dimensionality. These insights advance our understanding of supramolecular assembly principles in porphyrin-based materials and offer new pathways for developing high-performance frameworks for applications in catalysis, sensing, and materials science.

Isotopological entanglement of a metal–organic framework and a hydrogen-bonded organic framework for proton conduction

Isotopological entanglement of a metal–organic framework and a hydrogen-bonded organic framework for proton conduction

Pressure-Modulated Luminescence Enhancement and Quenching in a Hydrogen-Bonded Organic Framework.

Light emission in the solid state is central for illumination, sensing, and imaging applications. Unlike luminescence in dilute solutions, where the excited states are unimolecular in nature, intermolecular interaction plays a significant role in the quantum yield of solid-state luminophores, manifested as competing aggregation-caused quenching (ACQ) and aggregation-induced enhancement (AIE). Both effects are extensively studied in various systems; however, it remains unclear how their competition depends on molecular conformation and intermolecular stacking. Here the direct observation of pressure-modulated AIE-ACQ competition in a crystalline hydrogen-bonded organic framework (HOF) is reported. Using in situ spectroscopies and computational modeling, the intramolecular vibration and intermolecular π-π stacking directly responsible for the non-radiative decay of the excited state are identified. The extent of these two contributions is modulated by hydrostatic pressure and guest molecules in the HOF pores. This work demonstrates a physically neat model system to understand and control solid-state luminescence, and a potential material platform for piezoluminescent sensing.

Efficient Methane Purification Using a Robust and Recoverable Hydrogen-Bonded Organic Framework.

Efficient separation and purification of methane is a key step in promoting its wide application as an environmentally friendly energy carrier and an important chemical raw material. Development of single solid adsorbents simultaneously combining robust structure, high separation capacity, and easy performance recovery is highly desired but quite a challenge for realizing methane depuration. In the present study, we report an ultramicroporous hydrogen-bonded organic framework compound constructed from a tetracyano bithiophene-functionalized ligand. Similar to the acting principle of enzymes, multisite supramolecular interactions endow the material with not only extraordinary chemical stability in wide pH range including 12 M HCl and 20 M NaOH solutions but also highly selective recognition of acetylene and carbon dioxide over methane. The packing densities and adsorption selectivities toward acetylene and carbon dioxide are the highest reported for the hydrogen-bonded organic framework materials. Dynamic breakthrough experiments demonstrate its highly efficient methane purification ability from binary and even ternary mixed gases, with not only methane productivities up to 2.34 mol kg-1 but also moderate regeneration energy. Furthermore, the title compound can be easily regenerated in almost quantitative yield via simple rato-evaporation of its dichloromethane solution once its activity is attenuated or lost.

Efficient SERS Substrate HOF@Au in Conjunction with DNAzyme-Mediated DNA Walker as a Signal Amplifier for the Ultrasensitive Detection of Lomefloxacin.

Lomefloxacin (LOM) is an efficacious antibiotic that might lead to liver damage and other adverse reactions if consumed over an extended period. Hence, this study proposed a DNAzyme-mediated DNA walker as a signal amplifier in combination with a substantial quantity of Au nanoparticle (NP)-loaded hydrogen-bonded organic frameworks (HOFs) as a surface-enhanced Raman scattering (SERS) substrate to accomplish the highly sensitive detection of LOM in food. Crucially, due to their high specific surface area and strong adsorption capacity, HOFs act as an ideal substrate for the in situ growth of a large amount of Au NPs, which exhibit a robust and uniform SERS enhancement. Once the target LOM was presented, the DNAzyme was activated to start the DNA walker and produce single DNA in abundance, which further triggered the catalytic hairpin assembly (CHA) cycle. In addition, the multi-interstitial core-shell structure of Au@Ag@4-nitrobenzenethiol (4-NTP)@Au@Hp3 produced more SERS "hot spots" and significantly amplified the local electromagnetic field, with HOF@Au synergistically strengthening the Raman signal of 4-NTP. Using this principle, this sensor achieved the ultrasensitive detection of LOM through the "signal on" strategy, with a detection limit as low as 4.62 × 10-14 mol/L. This strategy explored a meaningful innovative path for the design of a novel SERS biosensor for the sensitive and selective detection of antibiotics in food.

Epoxy resins with enhanced mechanical and flame-retardant properties through P/N hydrogen-bonded organic frameworks for wood and steel coatings

Epoxy resins with enhanced mechanical and flame-retardant properties through P/N hydrogen-bonded organic frameworks for wood and steel coatings

Lewis acid-optimized hydrolysable catalytic binder with dynamic hydrogen-bonded framework for durable lithium-sulfur batteries

Lewis acid-optimized hydrolysable catalytic binder with dynamic hydrogen-bonded framework for durable lithium-sulfur batteries

A Water-stable Hydrogen-Bonded Organic framework (HOF) for Selective Sensing of Antibiotics in Aqueous Medium.

Although metal organic frameworks (MOFs) and covalent organic frameworks (COFs) have been extensively used as fluorescent-based antibiotic sensors, newly developed hydrogen-bonded organic frameworks (HOFs) are largely unexplored toward this direction. To realize this, the luminescent HOFs must be stable in water as the analytes are mostly found in water-based effluents in environments. In addition, HOFs should be equipped with specific recognition sites in order to direct the discrimination among the antibiotics. Herein, we report a 3D porous HOF, IITKGP-HOF-6, constructed from an aromatic-rich tetratopic carboxylic acid (H4L), which exhibits excellent hydro and prolonged open-air stability (7 and 15 days, respectively). IITKGP-HOF-6 was explored for the highly selective detection of nitrofurans (NFs) family of antibiotics in aqueous medium exhibiting a remarkably low detection limit of 0.75 µM for nitrofurazone (NFZ) through luminescence quenching. Photoinduced electron transfer driven by the presence of low-lying charge-transfer excited state below to the [[EQUATION]] and Forster energy transfer between H4L donor and NFZ acceptor are confirmed to be responsible for observed quenching using detailed quantum-chemical studies. This work demonstrates the usage of HOFs as sensory materials toward antibiotics in aqueous medium along with a clear understanding into the sensing mechanism at the molecular level.

Metal-Dilution Effect on Spin Transition Behavior of Solvated/Desolvated Hydrogen-Bonded Cobalt(II)-Organic Frameworks.

Terpyridine-based cobalt(II) complex, [CoII(HL)2] (1; H2L = 2,2':6',2″-terpyridine-5,5″-diyl dicarboxylic acid), forms a hydrogen-bonded diamond framework with solvent absorption and desorption capabilities. The desolvated form (1·desolv) exhibits spin transition (ST) behavior accompanied by thermal hysteresis. To investigate the effect of metal-dilution, an Fe2+ center, which has a low-spin state (S = 0) and coordinates to two terpyridine moieties, was introduced. The resulting complexes, [CoII x FeII 1-x (HL)2], where x = 0.88 (2), 0.55 (3), and 0 (4), demonstrated a significant influence of metal-dilution on the desolvated forms, but not on the solvated forms. Namely, the spin state is more strongly affected by the presence of solvent than by metal-dilution. However, in the absence of solvent, the Fe2+ ratio significantly impacts the ST behavior.

Optimized Photochromic Performance of Spiropyran through Incorporation into Hydrogen-Bonded Organic Frameworks and Applications in Anticounterfeiting and Information Encryption.

Photostimulus-responsive fluorescent materials are promising for anticounterfeiting and UV printing due to rapid response and simple preparation. In this paper, we propose a novel strategy to prepare photostimulus-responsive materials SP@HOF-olefin by integrating the photochromic molecule spiropyran (SP) with postsynthetic modified hydrogen-bonded organic frameworks (HOF-olefin). Compared to SP@HOF, the composites SP@HOF-olefin exhibit enhanced photochromic properties, such as a fast response speed, pronounced color contrast, and exceptional fatigue resistance. The improvements can be attributed to the reduction of residual carboxyl groups in the framework, which subsequently decreases the polarity of the framework. Besides, the SP loading content in SP@HOF-olefin was significantly enhanced. Furthermore, HOF-olefin can be transformed into HOF films via photopolymerization. These films demonstrated excellent flexibility, which can be folded and twisted at any angle ranging from 0 to 180°. By utilizing the photomask method, letters such as "Z", "T", "S", and "U", along with other patterns were successfully imprinted on the film. Besides, we investigated the utilization of these films in advanced anticounterfeiting applications. This work serves as a representative case demonstrating how functionalized HOFs improved the photochromic properties of SP, showcasing potential applications in anticounterfeiting and information encryption.

Channel-Assisted Hydrogen-Bonded Organic Frameworks for Enhanced Proton Conduction Against Weak Humidity

Channel-Assisted Hydrogen-Bonded Organic Frameworks for Enhanced Proton Conduction Against Weak Humidity

Hydrogen-Bonded Organic Framework Films Integrated with Wavy Structured Design for Wearable Bioelectronics.

The integration of hydrogen-bonded organic frameworks (HOFs) with flexible electronic technologies offers a promising strategy for monitoring detailed health information, owing to their inherent porosity, excellent biocompatibility, and tunable catalytic capabilities. However, their application in wearable and real-time health monitoring remains largely unexplored, primarily due to the mechanical mismatch between the traditionally fragile HOFs particles and the softness of human skin. Herein, this study demonstrates an epidermal biosensor that maintains reliable sensing capability even under extreme deformation and complex environmental conditions by integrating HOFs films with wavy bioelectrodes. This wearable biosensor demonstrates ultrasensitive detection capabilities, with a limit of detection of 49.64nM, and accurately measures nutritional content in sweat while conforming to curved skin surfaces. The sensor's performance is comparable to those obtained using high-performance liquid chromatography (HPLC). More strikingly, scratched HOFs films can be regenerated through a simple solvent rinsing process, enabling their reuse in the fabrication of new biosensors and offering a significant advantage over conventional sensing materials. This work has the potential to inspire the development of more flexible electronic devices, leveraging the structural adaptability and diversity of HOFs for personalized healthcare applications and real-time health monitoring.

High-performance solid-state proton gating membranes based on two-dimensional hydrogen-bonded organic framework composites

Biological ion channels exhibit strong gating effects due to their zero-current closed states. However, the gating capabilities of artificial nanochannels have typically fallen short of biological channels, primarily owing to the larger nanopores that fail to completely block ion transport in the off-states. Here, we demonstrate solid-state hydrogen-bonded organic frameworks-based membranes to achieve high-performance ambient humidity-controlled proton gating, accomplished by switching the proton transport pathway instead of relying on conventional ion blockage/activation effects. Density functional theory calculations reveal that the reversible formation and disruption of humidity-induced water bridges within the frameworks facilitates the switching of proton transport mode from the adsorption site hopping to the Grotthuss mechanism. This transition, coupled with the introduction of bacterial cellulose to enhance desorption/adsorption of water clusters, enables us to achieve a superior proton gating ratio of up to 5740, surpassing state-of-the-art solid-state gating devices. Moreover, the developed membrane operates entirely on solid-state principles, rendering it highly versatile for a myriad of applications from environmental detection to human health monitoring. This study offers perspectives for the design of efficient proton gating systems.

Stabilization of Alkyltin γ-Keggin Clusters by 2, 5-Dihydroxyterephthalate Ligands.

The Keggin clusters are one kind of the most representative molecular structures in the field of metal-oxo clusters. Although the different types of Keggin clusters with various components were reported, the research about γ-Keggin isomer remains less developed. This is ascribed to the difficulty in obtaining the stable pure γ-Keggin cluster for the structural isomerization. In this study, we adopted a ligand stabilization strategy to get the stable pure γ-Keggin structure [(n-BuSn)12(NaO4)(OH)24](DHTA)2.5·DMF·H2O (CTGU-SnC-10). Different from the reported mixed neutral-charge alkytin β, γ isomers, the NaSn12 cluster in the CTGU-SnC-10 is a cationic pentavalent γ-Keggin structure without isomerization. Besides the electrostatic interaction, the NaSn12 cationic clusters have a strong hydrogen-bond interaction with polycarboxylic ligands, resulting in the formation of a 3D hydrogen-bonded framework. These are conducive to stabilizing the γ-Keggin structure. Moreover, the CTGU-SnC-10 exhibits high hydrophobicity and a small band gap due to the organic functional groups of the framework.

Pi-Stacking Geometry Directed Supramolecular Secondary Building Units Shaping Hydrogen-Bonded Frameworks for Intensive NH3 Adsorption.

Exploiting supramolecular secondary building units (SSBUs) for developing porous crystalline materials represents an exciting breakthrough that extends the boundaries of reticular chemistry. However, shaping polynuclear clusters sustained by non-covalent interactions for the assembly of hydrogen-bonded frameworks remains a critical challenge. This study presents a novel strategy to stabilize SSBUs by tuning the π-stacking geometry of conjugated building blocks, facilitating the creation of hydrogen-bonded frameworks with tailored architectures for demanding gas separation. Specifically, parallel-displaced π-π stackings of aromatic heterocycles bearing carboxyls promote the formation of SSBUs bridged by ammonium cations [NH4+]8[COO-]8 (SSBU-4), enabling the assembly of hydrogen-bonded frameworks with permanent porosity and structural diversity influenced by the solvent effect. Comparatively, the non-heterocyclic building units exhibit geometrically- or energetically-unfavorable π stackings, resulting in fragile frameworks that collapse after removing disordered guests. Significantly, the heterocycle conjugated frameworks contain abundant open Brønsted acid N-H sites within pore channels, demonstrating remarkable NH3 adsorption ability among diverse industrial gases with a high capacity (275.7 mL/g, at 273 K, 100 kPa) as compared to reported porous molecular crystals.

Capturing Alkanes from Natural Gas by Using a Hydrogen-bonded Organic Framework Composed of Tetracarboxylic Acid

Capturing Alkanes from Natural Gas by Using a Hydrogen-bonded Organic Framework Composed of Tetracarboxylic Acid

Hydrogen-Bonded Organic Framework Nanosheets with Rich Free Oxygen Atoms for NO2 Sensing.

Hydrogen-bonded organic frameworks (HOFs) are under fast development in broad applications but have not been well explored for chemiresistive gas sensing yet primarily due to insufficient active sites. Herein, a new porphyrin-based HOF-199 is constructed by OH···O hydrogen bonds featuring layered networks and rich free oxygen (O) atoms, which is further exfoliated into few-layer nonosheets with more dangling O sites through an ultrasound-assisted liquid exfoliation method (namely L-HOF-199). Benefiting from rich electron-donor sites, L-HOF-199 demonstrates exceptional NO2 sensing properties under ambient conditions, achieving a remarkable 3.25-fold improvement in sensitivity (152% toward 5 ppm of NO2) and a faster response speed (52 s), relative to HOF-199. This work provides a promising platform for the rational design of advanced gas sensors via functional HOF chemistry.

Laboratory Studies of the Clathrate Hydrate Formation in the Carbon Dioxide-Water Mixtures at Interstellar Conditions.

This study investigates the formation of carbon dioxide clathrate hydrates under conditions simulating interstellar environments, a process of significant astrophysical and industrial relevance. Clathrate hydrates, where gas molecules are trapped within water ice cages, play an essential role in both carbon sequestration strategies and understanding of the behavior of ices in space. We employed a combination of Fourier Transform Infrared (FTIR) spectroscopy, mass spectrometry, temperature-programmed desorption (TPD), and Density Functional Theory (DFT) calculations to explore thin films of H2O:CO2 ice mixtures with varying CO2 concentrations (5-75%) prepared by vapor deposition at temperatures ranging between 11 and 180 K. The study revealed the influence of CO2 concentration and deposition temperature on the formation mechanism of diverse structures, including clathrate hydrates, polyaggregates, and segregated CO2 groups. Spectral features associated with CO2 encapsulation in clathrate hydrates were observed at 2335, 2349, and 3698 cm-1 in the 5 and 15% mixtures after deposition at 11 K and after warming at temperatures above 100 K. The observed increase in CO2 sublimation temperature to 145-155 K and co-condensation of CO2 molecules at 172 K with water molecules at a pressure of 0.5 μTorr can be attributed to the encapsulation of CO2 molecules within the robust hydrogen-bonded framework of the clathrate cages under specific conditions. These findings enhance our understanding of the intricate processes involved in clathrate and hydrate formation in CO2 and H2O mixtures, shedding light on their physical properties and the dependence of their specific characteristics on the formation method.