Owing to the critical roles it plays for both structure and functionality, hydrogen bonding has high hopes for the orientated applications in hydrogen-bonded organic frameworks (HOFs). Here in this work, a hydrogenbonding strategy is performed for adjusting the structure and functionality of a heme-like ligand meso-tetra(carboxy-phenyl)-porphyrin (TCPP) with co-former 1,3-di(4-pyridyl) propane (1,3-DPP). A 3D dynamic HOF TCPP-1,3-DPP, with permanent porosity is obtained. For this HOF, the two components form novel robust 1D porous stripes, with the 1,3-DPP molecules acting as the lining for the pores that are confined within the region between adjacent carboxyphenyl moieties of TCPP. This confinement has tuned the affinities of TCPP from hydrophobic into hydrophilic. Interestingly, the 1D stripes are further stacked by weak π…π interactions into a 3D framework, the latter is highly dynamic with 1D stripes sliding back and forth, upon pressurized and water adsorption in the solid-state under ambient conditions, respectively. The activated TCPP-1,3-DPP has a Brunauer-Emmett-Teller surface area of 258 m 2 g −1 , and shows a maximum adsorption capacity about 9.8% for water during the adsorption-desorption cycles, demonstrating a promising candidate for the real-world application in effective dehydration of industrial gases under ambient conditions.

The currently involved two-dimensional materials (2DMs) are referred to as atomically thin-layered materials, which are composed of in-plane covalent or coordinated crystalline sheets with different chemical compositions and crystal structures. However, if the crystalline sheets supported by in-plane noncovalent intermolecular interactions, such as hydrogen-bonding, van der Waals, etc., can be exfoliated into stable atomically thin nanosheets, then the category and members of the 2DM family will be expanded significantly and extensively. Here we demonstrate that, through an ultrasonic force-assisted top-down fabrication technology in the aqueous solution, the three-dimensional hydrogen-bonded organic framework (HOF) TCPP-1,3-DPP, which is composed of onedimensional (1D) porous ribbons that are held together via robust hydrogenbonding contacts, can be exfoliated into atomically thin 1D porous nanoribbons (nr-HOF), providing a fine-dispersed stable colloidal suspension with a significant Tyndall effect and ultrahigh surface sensitivity. In addition, the fully exposed surface and strong surface adsorption ability of nr-HOF account for the high loading capacity of doxorubicin (Doxo; 29.4%, nr-HOF@Doxo), providing a smart carrier for an anticancer drug featuring the desired synergistic chemotherapy−photodynamic therapy−photothermal therapy effects that is more effective than the commercial Doxo drug, with a cell viability as low as 1.3%. All of these results have demonstrated brand-new 2DMs with appealing properties and applications.

A thermal-induced dielectric switching has been realized in two ion-pair crystal [CHN]·[HPO] (1, CHN = 3,5-diamino-1,2,4-triazolinium) through single-crystal-to-single-crystal phase transition (SCSC-PT). Upon cooling from room temperature, the 1D cation stripes that are composed of [CHN] cations have undergone a 90° sharp rotation around the c axis, accompanied by the transition of crystal stacking from loose unparallel (dynamic state) to compression parallel (static state) and reorientation of dipoles on the [CHN] cation, which thus resulted in high dielectric state to low dielectric state transformation. While on the warming run, the reverse process was rather sluggish, resulting in a reversible dielectric switching with ultralarge (about 40K wide) hysteresis loop near room temperature. It is thought that the large-sized polar cation stripes have a predominant influence on the switching properties of 1.

Through a facile-operating ultrasonic force-assisted liquid exfoliation technology, the single-layered two-dimensional (2D) [Co(CNS)(pyz)] (pyz = pyrazine) nanosheets, with a thickness of sub-1.0 nm, have been prepared from the bulk precursors. The atomically thickness and the presence of abundant sulfur atoms with high electronegativity arrayed on the double surfaces of the sheets are making this kind of 2D MOF (metal-organic framework) nanosheets highly sensitive to intermolecular interactions. As a result, it can be well dispersed in all kinds of solvents to give a stable colloidal suspension that can be maintained for at least one month, accompanied by significant solvatochromic behavior and various optical properties, which thus have shown the potential to be practically applicated as in situ visual test paper for solvent identification and solvent polarity measurements. More importantly, combined with a smartphone, this kind of 2D-MOF nanosheets can be developed into in situ visual test paper to identify isomers and determine the polarity of mixed solvents quantitatively and qualitatively, suggesting the promising application of a portable, economical, and in situ visual test strategy in real world.

Bidirectional photoswitching of molecular materials under ambient condition is of significant importance. Herein, we present for the first time that a core-shell UCNP-SCO nanosphere (UCNP = upconversion nanophosphor, SCO = spin crossover), which was composed of a UCNP core (NaYF: 20 mol % Yb, 1 mol % Er) and an SCO iron(II) shell ([Fe(HBpz)(bipy-COOH)], HBpz = dihydrobis(1-pyrazolyl)borate, bipy-COOH = 4,4'-dicarboxy-2,2'-bipyridine), can be reversibly photoswitched between the high-spin and low-spin states at room temperature in the solid state, via alternating irradiation with near-infrared (λ = 980 nm) and ultraviolet (λ = 310 nm) light. What's more, this reversible spin-state switching was accompanied by a variation of fluorescent spectrum and dielectric constants. The strategy here, that is, integrating the SCO iron(II) complex into a UCNP-SCO nanosphere for molecular photoswitching, may open a new area in the development of photocontrolled molecular devices.

Fine tuning of the structures and properties of hydrogen-bonded organic frameworks (HOFs) has been considered to be a huge challenge. Herein, we reported the controlled synthesis of meso-tetrakis­(carboxyphenyl)­porphyrin (TCPP)-based HOFs via a “counterstrategy” of blocking the strong hydrogen-bonded building units on the TCPP backbones. Mediated by the temperatures, both the kinetically and thermodynamically favored HOF products TCPP-2­(DMF), TCPP-4­(DMF), and TCPP-6­(DMF) can be obtained under 120, 130, and 140 °C, respectively. Results revealed that the numbers and binding positions of end-capped N,N-dimethylformamide (DMF) molecules not only played a key role in the thermal stability and permanent porosity of the present HOFs but also affected significantly the photocatalytic activities for the degradation of 9,10-diphenylanthracene, where a positive correlation between the numbers of DMF molecules and the photocatalytic activities has been established, which can be attributed to variation of the intermolecular van der Waals forces. In addition, upon removal of the lattice water and extra DMF molecules, respectively, HOFs TCPP-2­(DMF) and TCPP-6­(DMF) can be transformed into a polymorph TCPP-4­(DMF)* in the solid state, suggesting a dynamic TCPP-DMF skeleton. This work will promote significantly the development of porphyrin-based HOFs and porphyrin-based photocatalysis materials.

Combining the fascinating advantages of ultrathin two-dimensional (2D) nanosheets with the nanostructuration of spin-crossover (SCO) materials represents an attractive target of controlled fabrication of SCO nano-objects at the device level. Here, we demonstrate that through facile-operating ultrasonic forceassisted liquid exfoliation technology the three-dimensional (3D) van der Waals SCO bulk precursor {[Fe(1,3-bpp) 2 (NCS) 2 ] 2 (1, 1,3-bpp = 1,3-di(4-pyridyl)propane)} can be exfoliated into single-layered 2D nanosheets (NS-1). As a consequence, the magnetism has been tuned from complete paramagnetic (bulk precursors) to SCO transition at around 250 K (2D nanosheets). In addition, the metal-to-ligand charge transition (MLCT), the intraligand π−π* transition and the color display also have been altered both in colloidal suspension and in the solid state. These dramatic changes of physical−chemical properties at different forms and states can be attributed to the efficient cooperativity derived from the interlayer van der Waals interactions within the curly or vertically stacked 2D building blocks.

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