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CO2 capture and storage have been regarded as promising concepts to reduce anthropogenic CO2 emissions. However, the high cost, inferior adsorption capacity, and higher effective activation temperature of traditional sorbents limit their practical application in efficient CO2 capture. Here, a C‐S‐H@ZIF‐8 (C‐S‐Z) sorbent is fabricated by in situ growth of the ZIF‐8 shell on the C‐S‐H (calcium‐silicate‐hydrate) surface for ultra‐high CO2 adsorption and storage. Among the C‐S‐Z, the outer ZIF‐8 shell acts as a transport channel that promotes CO2 absorption toward the underlying C‐S‐H substrate for accelerated carbonation while preventing nitrogen and water from reaching the interior C‐S‐H. As a consequence, C‐S‐Z possesses the merits of ample pyrrolic nitrogen, porous structure, and ultra‐high surface area (577.18 m2 g−1), that contribute to an ultra‐high CO2 capture capacity, reaching 293.6 mg g−1. DFT calculations show a high CO2 adsorption energy and the mineral carbonation is dominant by the adsorption process. In particular, the advantages of the outstanding adsorption capacity, low cost, and high CO2 selectivity make this C‐S‐H‐based sorbent hold great potential in the practical application for direct air CO2 capture and storage. [ABSTRACT FROM AUTHOR]

Smart materials and devices play an increasingly important role in improving modern life due to their richer functions, enhanced controllability, and improved biocompatibility. Herein, calcium silicate hydration (C–S–H) is integrated with layered [Co(NCS)2(pyrazine)2]n metal–organic frameworks (Co–MOF) and polymeric skeleton to fabricate the smart building material (M–C–S–H). C–S–H was anchored on the polymeric skeleton to reinforce the network structure for enhanced mechanical strength and toughness. Simultaneously, the highly porous skeleton structure enables the uniform distribution of layered Co–MOF, which could maintain its molecular form to endow the M–C–S–H with the photoresponsive color‐switching performance. The M–C–S–H as a smart building material exhibits the color change between light blue and black blue upon near‐infrared illumination on/off within a wide temperature range to achieve personalized wall and building decoration. Taking advantage of the low cost, rapid response, outstanding reversibility, and good color stability, M–C–S–H could provide lively, dynamic, and changeable decorating effects for walls and buildings. [ABSTRACT FROM AUTHOR]

Iron(II)-triazole coordination polymers have attracted considerable interest for their synthetic versatility, which allows tuning their spin-crossover (SCO) properties. Embedding SCO solid particles in sponge matrices is a simple, powerful, and generic approach to construct processable SCO materials. Here, we have studied a series of magnetic frameworks based on partial ligand substitution by using different chemical mixtures of two organic ligands, yielding four isostructural coordination polymers. The integration of the hygroscopic SCO material has endowed the composite sponge with the ability to capture moisture under ambient conditions. In particular, not only does a spin-crossover transition during absorption occur, but also a color variation has been achieved by varying humidity. The consequences of cooperativity and the exposed surface of the composite sponge on the spin transition were evaluated and the most promising materials among them were screened. This work provides guiding significance for the fabrication and practical application of spin-crossover-sponge materials. [ABSTRACT FROM AUTHOR]

Triggering the spin-state switching (SSS) in solutions at room temperature (RT) has attracted attention in the field of molecular switches. Herein, we report the preparation and switching properties of a ferrous complex Fe(H2Bpz2)2(L -C2H5) (H2Bpz2 = dihydrobis(1-pyrazolyl)borate, L -C2H5 = (4,15-bis[4-(N,N-diethylamino)phenyl][1,2,5]thiadiazolo-[3,4-i]dipyrido[a,c]phenazine)). Upon near-infrared (NIR) laser on, the ferrous complex formed H-aggregation in the solution with enhanced ligand-to-ligand charge transfer, which thus achieved a high-spin state. Upon switching the NIR laser off, the ferrous complex changed to J-aggregation with enhanced intramolecular charge transfer, which resulted in the low-spin state; as a consequence, charge transfer triggered reversible SSS in the solution at RT. More interestingly, further confinement into the solid-state three-dimensional polymer sponge did not affect the SSS performance of the ferrous complex, suggesting the high potential of Fe(H2Bpz2)2(L -C2H5) for practical applications in future molecular electronic and spintronic devices. [ABSTRACT FROM AUTHOR]

Converting Cr(VI) to Cr(III) and subsequent precipitation of Cr(III) represents an efficient approach for wastewater treatment. Although it is possible to eliminate Cr(III) by adjusting the pH to elicit precipitation, this method is expensive and can lead to secondary pollution. Herein, we report a composite (C-S-U) composed of calcium silicate hydrate (C-S-H) and UiO-66-NH2 nanoparticles (UN NPs). We demonstrated a remarkable synergistic effect for the purification of total chromium concentration (Cr(T)) attributed to the affinity of Cr(III) to C-S-H, coupled with the Cr(III) sorption-enhanced photocatalysis. C-S-U exhibited a significantly enhanced photocatalytic rate (0.052 min−1) for Cr(VI) but also delivered outstanding sorption capacity (217.9 mg g−1) towards Cr(III). Cr(T) could be reduced to an ultra-low level (∼0.007 mg L−1) within 90 min. Meanwhile, regeneration of Cr(III)-passivated C-S-U and Cr recollection was achieved. Electrochemical analysis and X-ray photoelectron spectroscopy were undertaken to reveal the mechanism of removal. [ABSTRACT FROM AUTHOR]

Metal–organic framework nanosheets (MONs) are expected to turn the cornerstone of integrated electronic and optoelectronic devices owing to their unique properties. However, as the premise and guarantee for research applications, adjustable preparation and accurate control of MONs remain a challenge. Here in this work, we demonstrate that the sizes and colors of MONs can be tuned by subtle control of the solution pH (from 3 to 11) during the precursor preparation. Where the variation of the sizes of MONs from nano-scale (lateral size smaller than 200 nm) to micro-scale (lateral size larger than 10 μm) was achieved, which was accompanied by the continuous color variation from green to gray for the solid-state samples, and from orange to pink for the colloidal suspensions. As a result, linear correlations between the sizes and colors of the MONs with the solution pH were established. Laser irradiation experiments further demonstrated the inverse relationship between the fluorescence intensity of MONs and the pH, providing a fairly good strategy for the controlled preparation and color adjustment of MONs. [ABSTRACT FROM AUTHOR]

Photoreversible color‐switching materials, which can reversibly change color in response to external light stimuli, have attracted increasing attention for their applications in time‐sensitive information storage and optical data storage fields. But most of the related materials are dyes or redox compounds with ultraviolet as the light source, dramatically limiting the cycling stability during discoloration processes. To address this problem, a near‐infrared (NIR)‐responsive rewritable paper via doping layered Co‐metal–organic frameworks (MOFs) into the stable polyvinylidene fluoride matrix is reported for the first time. Layered Co‐MOF shows a rapid color‐switching characteristic between orange and black blue upon NIR illumination on/off because of the interlayer spacing changes. Benefiting from the soft network structures of the matrix, Co‐MOF can be homogeneously distributed to deliver an outstanding reversibility performance, including rapid response, coloration in a short period, and decoloration within about 3 min in ambient air. The fabrication of new photoreversible color switching system holds great potential in communication security, which offers a viable pathway to achieve ink‐free photoreversible printing. [ABSTRACT FROM AUTHOR]

Efficient atmospheric water harvesting has been a focal point in the broad spectrum of water collection sources, to alleviate the challenges caused by water shortage. Herein, we report a systematic approach focused on preparing a polymer hydrophobic–hydrophilic gel, doped with super hygroscopic materials (SHMs), enabling high moisture capture, color response, and in situ moisture storage. The hybrid gel quickly achieves a water uptake of 100% under different humidity levels from 43% to 98%. The hybrid gel achieves not only the capture of moisture but also the response of an obvious color change from blue to pink, visible to the naked eye. The interesting properties of the hybrid gel give rise to a wide range of possibilities in design and engineering for humidity capture response and detection application, providing bright prospects for the next generation of atmospheric water harvesting systems. [ABSTRACT FROM AUTHOR]

Humidity visualization is of significant importance across both the living systems and the industrial processes, which remains a huge challenge. Herein, for the first time, a hydrophilic sponge, which is composed of rigid gel and super hygroscopic material, has been demonstrated capable of all‐weather humidity visualization in a portable, convenient, economical, and in situ manner. This promising aspect is attributed to the effective all‐weather humidity capture and various color display as a response to the humidity capture capacity, of the super hygroscopic material; as well as the rapid humidity transport and excellent humidity storage ability provided by the porous rigid gel. As a consequence, combined with a smartphone, the invisible information on the environment's relative humidity levels, on the one hand, can be correlated qualitatively with the specific color display of the sponge; on the other hand, it can be correlated quantitatively with the specific color intensity, providing a pretty good smart model for humidity visualization in various complex environments. The present humidity visualization technology may open up a new avenue for the development of novel humidity sensors with a wide range of practical applications. [ABSTRACT FROM AUTHOR]

The practical application of molecular switches is highly dependent on the reversible spin-state switching under ambient conditions, which needs a delicate materials design. Here, by confining a spin-crossover material into a sponge, the challenging goal of reversible spin-state switching in the solid state under ambient conditions has been realized, upon irradiation with a 980 nm laser for 120 s followed by shutting off the laser for 150 s. More importantly, further integration of the hygroscopic material has endowed the sponge with the merits of effective atmospheric humidity-triggered reversible spin-state switching under ambient conditions for the first time, accompanied by a reversible color variation upon naturally occurring humidity capture/release cycles. This work is expected to provide a fairly good strategy for developing novel molecular switches triggered by natural energy sources at the device level. [ABSTRACT FROM AUTHOR]

By using in-site generated formate, 2D HOFs of TCPP, with excellent stability and permanent porosity (BET surface area larger than 560 m2 g−1), have been obtained. The constructed 2D square-like TCPP-HCO2 grid sheets have shown considerable in-plane stability that comparable to the TCPP-based 2D MOFs, that can be exfoliated into atomically thin 2D nanosheets with efficient photocatalytic activity in aqueous system. These results are expected to shed light on the application-orientated one-pot synthesis for new kinds of multi-dimensional HOFs. [ABSTRACT FROM AUTHOR]

Precise revealing the mechanisms of excited‐state intermolecular proton transfer (ESPT) and the corresponding geometrical relaxation upon photoexcitation and photoionization remains a formidable challenge. In this work, the compound (E)‐4‐(((4H‐1,2,4‐triazol‐4‐yl)imino)methyl)‐2,6‐dimethoxyphenol (TIMDP) adopting a D‐π‐A molecular architecture featuring a significant intramolecular charge transfer (ICT) effect has been designed. With the presence of perchloric acid (35 %), TIMDP can be dissolved through the formation of a HClO4–H2O–OH(TIMDP)–N(TIMDP) hydrogen‐bonding bridge. At the ground state, the ICT effect is dominant, giving birth to crystals of TIMDP. Upon external stimuli (e.g. UV light irradiation, electro field), the excited state is achieved, which weakens the ICT effect, and significantly promotes the ESPT effect along the hydrogen‐bonding bridge, resulting in crystals of [HTIMDP]+⋅[H2O]⋅[ClO4]−. As a consequence, the mechanisms of the ESPT can be investigated, which distorted the D‐π‐A molecular architecture, tuned the emission color with the largest Stokes shift of 242 nm, and finally, high photoluminescence quantum yields (12 %) and long fluorescence lifetimes (8.6 μs) have achieved. These results not only provide new insight into ESPT mechanisms, but also open a new avenue for the design of efficient ESPT emitters. [ABSTRACT FROM AUTHOR]