ABSTRACT The crystallization pathways of metal phosphonate frameworks (MPFs) remain poorly understood because the strong coordination ability of phosphonate ligands often leads to rapid precipitation, making the isolation of transient intermediates challenging. Herein, we report two 3D Cu‐based MPFs, [Cu 2 (amp 2 H 2 )]·2H 2 O·DMF ( Cu‐3D ) and [Cu 2 (INA) 2 (amp 2 H 2 )(H 2 O) 2 ] ( Cu‐INA‐3D ), where amp 2 H 4 is photodimerized 9‐anthracenemethylphosphonic acid and INAH is isonicotinic acid. By shortening the reaction time, we isolated a metastable intermediate, [Cu 2 (INA) 2 (amp 2 H 2 )]·2H 2 O ( Cu‐INA‐2D ), which can gradually transform into the thermodynamically more stable Cu‐INA‐3D phase via reconstruction of the Cu–PO 3 connectivity and reorganization of the {Cu(INA)} chains. The crystals of Cu‐INA‐2D can undergo solvent‐assisted cleavage to yield an accordion‐like morphology. Further, thermal de‐dimerization of the dianthracene units in Cu‐3D and Cu‐INA‐3D induces framework transformation, generating new phases containing anthracene moieties. We studied the photothermal properties of Cu‐3D , Cu‐INA‐3D and their de‐dimerized products. All exhibited near‐infrared (NIR) photothermal responses under 808 nm laser irradiation. Benefiting from its photothermal conversion capability and the redox activity of Cu II centers, Cu‐INA‐3D was employed to serve as a photothermally driven catalyst for pyrrole polymerization. These findings provide insight into the crystallization mechanism of copper diphosphonate frameworks and demonstrate the potential of dianthracene‐based MPFs as multifunctional photothermal materials.
ABSTRACT Electrochemical conversion of CO 2 and nitrate into urea offers a sustainable route for nitrogen fixation, yet the reliability of catalytic performance evaluation is frequently compromised by inaccurate product quantification. Current detection methodologies are susceptible to severe interferences from electrolyte pH fluctuations, byproduct accumulation (e.g., NO 2 − , NH 3 ), and complex electrolyte factors. In this study, we systematically decouple the interference mechanisms affecting these mainstream detection methods, revealing that extreme pH conditions lead to significant quantitative deviations in urease‐based assays due to enzymatic denaturation. To overcome these limitations, we establish a comprehensive calibration strategy and a multi‐method synergistic detection protocol. This approach integrates targeted pH optimization with a logic‐guided selection of analytical techniques based on specific concentration ranges and impurity profiles. Validated using a BiOCl‐catalyzed urea synthesis system, this integrated protocol demonstrates exceptional accuracy, stability, and cross‐method consistency. By offering a standardized, high‐throughput‐compatible workflow for eliminating false positives and measurement errors, this work provides critical methodological support for the objective assessment of electrocatalytic urea synthesis.
ABSTRACT Near‐infrared (NIR)‐absorbing small‐molecule dyes are highly attractive for biological applications, including imaging, photothermal (PT), and photodynamic (PD) therapy. Among these, heptamethine cyanines are particularly promising, but their inherently low photostability (PS) remains a major limitation. While PS is recognized as critical for imaging, its importance for PT and PD performance is less well established. Moreover, reported PS values depend strongly on experimental conditions, making comparisons across studies challenging. Here, we systematically compare the PS of established and newly synthesized heptamethine cyanines using a carefully evaluated protocol designed to ensure reliable and reproducible measurements. We examine how commonly applied structural modifications affect PS and investigate the relationship between photosensitization of oxygen and photodegradation. We find no clear correlation between singlet oxygen generation, molecular structure, and PS, indicating that singlet oxygen is not the major pathway responsible for cyanine photodegradation. For selected dyes, we further investigate photoinduced heating and demonstrate that photostability is the limiting factor for all investigated compounds. These results highlight the critical importance of PS beyond imaging and suggest that photostability should be considered a key, yet often overlooked, parameter governing the performance of NIR dyes in photothermal and photodynamic applications.
ABSTRACT Controlling the interaction landscape of threefold π‐surfaces offers a promising strategy for directing multidirectional molecular packing. Triptycene‐tribenzoquinone, with its rigid three‐bladed framework, provides a suitable platform for exploring this concept. Here we report the synthesis of new fluoro‐, bromo‐, and iodo‐substituted triptycene‐tribenzoquinones, which, together with the previously reported chloro‐substituted derivative, constitute the complete series of hexahalogenated triptycene‐tribenzoquinones ( TT X ; X = F, Cl, Br, and I). Using this series, we systematically investigate the effects of peripheral halogenation on their electronic properties and solid‐state molecular packing. All derivatives exhibit reversible three‐step reduction with first reduction potentials comparable to those of the corresponding tetrahalogenated benzoquinones. Increasing halogen size enhances the anisotropy of the electrostatic surface potential, leading to progressively stronger σ‐hole character. Upon crystallization, different packing modes emerge depending on the interplay between the intrinsic threefold π‐surface geometry, halogen size, and σ‐hole character, with TT F , TT Cl , and TT Br , and TT I forming non‐layered packing, layered rectangular 2D sheets, and a porous 3D network, respectively. These results demonstrate that peripheral halogenation reshapes the interaction landscape of threefold π‐surfaces while preserving their intrinsic redox properties, providing a design strategy for organizing molecular building blocks with multidirectional π‐surfaces into desired supramolecular architectures.
ABSTRACT The tetrasulfonated deep‐cavity calix[4]arene 1 , bearing a second row of benzene rings around its upper rim, self‐assembles into a dimeric capsule in water upon encapsulation of small hydrophobic guests. 1 H NMR spectroscopy shows that the two calixarene subunits interdigitate, creating an elongated hydrophobic cavity that accommodates linear and cyclic alkanes, as well as benzene and hexafluorobenzene. NMR competition experiments establish a guest size‐dependent stability sequence: among the linear alkanes, complex stability peaks at n ‐hexane and decreases for both shorter and longer homologs, whereas the cycloalkane complexes become steadily more stable from cyclopentane to cyclooctane, with the cyclooctane complex outcompeting the n ‐octane complex. Benzene forms a comparatively stable complex that is displaced by cyclohexane and cycloheptane, while hexafluorobenzene is in turn displaced by benzene. DFT calculations (BP86‐D4(COSMO = water)/def2‐SVP) of substitution energies and packing coefficients reproduce these trends qualitatively, particularly for the larger guests, and rationalize the guest size dependence in terms of a shift from single‐ to bis‐subunit CH···π contacts, and, for hexafluorobenzene, a central binding position that minimizes F···π interactions. Together, these results establish deep‐cavity calix[4]arene 1 as a versatile, hydrophobic effect‐driven capsule for the recognition of small apolar molecules in water.
