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Diamine-appended Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) metal-organic frameworks are a promising class of CO2 adsorbents, although their stability to SO2─a trace component of industrially relevant exhaust streams─remains largely untested. Here, we investigate the impact of SO2 on the stability and CO2 capture performance of dmpn-Mg2(dobpdc) (dmpn = 2,2-dimethyl-1,3-propanediamine), a candidate material for carbon capture from coal flue gas. Using SO2 breakthrough experiments and CO2 isobar measurements, we find that the material retains 91% of its CO2 capacity after saturation with a wet simulated flue gas containing representative levels of CO2 and SO2, highlighting the robustness of this framework to SO2 under realistic CO2 capture conditions. Initial SO2 cycling experiments suggest dmpn-Mg2(dobpdc) may achieve a stable operating capacity in the presence of SO2 after initial passivation. Evaluation of several other diamine-Mg2(dobpdc) variants reveals that those with primary,primary (1°,1°) diamines, including dmpn-Mg2(dobpdc), are more robust to humid SO2 than those featuring primary,secondary (1°,2°) or primary,tertiary (1°,3°) diamines. Based on the solid-state 15N NMR spectra and density functional theory calculations, we find that under humid conditions, SO2 reacts with the metal-bound primary amine in 1°,2° and 1°,3° diamine-appended Mg2(dobpdc) to form a metal-bound bisulfite species that is charge balanced by a primary ammonium cation, thereby facilitating material degradation. In contrast, humid SO2 reacts with the free end of 1°,1° diamines to form ammonium bisulfite, leaving the metal-diamine bond intact. This structure-property relationship can be used to guide further optimization of these materials for CO2 capture applications.

Diamine-appended Mg 2 (dobpdc) (dobpdc 4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) metal-organic frameworks are a promising class of CO 2 adsorbents, although their stability to SO 2 ─a trace component of industrially relevant exhaust streams─remains largely untested. Here, we investigate the impact of SO 2 on the stability and CO 2 capture performance of dmpn-Mg 2 (dobpdc) (dmpn = 2,2-dimethyl-1,3-propanediamine), a candidate material for carbon capture from coal flue gas. Using SO 2 breakthrough experiments and CO 2 isobar measurements, we find that the material retains 91% of its CO 2 capacity after saturation with a wet simulated flue gas containing representative levels of CO 2 and SO 2 , highlighting the robustness of this framework to SO 2 under realistic CO 2 capture conditions. Initial SO 2 cycling experiments suggest dmpn-Mg 2 (dobpdc) may achieve a stable operating capacity in the presence of SO 2 after initial passivation. Evaluation of several other diamine-Mg 2 (dobpdc) variants reveals that those with primary , primary (1°,1°) diamines, including dmpn-Mg 2 (dobpdc), are more robust to humid SO 2 than those featuring primary , secondary (1°,2°) or primary , tertiary (1°,3°) diamines. Based on the solid-state 15 N NMR spectra and density functional theory calculations, we find that under humid conditions, SO 2 reacts with the metal-bound primary amine in 1°,2° and 1°,3° diamine-appended Mg 2 (dobpdc) to form a metal-bound bisulfite species that is charge balanced by a primary ammonium cation, thereby facilitating material degradation. In contrast, humid SO 2 reacts with the free end of 1°,1° diamines to form ammonium bisulfite, leaving the metal-diamine bond intact. This structure-property relationship can be used to guide further optimization of these materials for CO 2 capture applications.

Chiral organic-inorganic perovskites (COIPs) have recently attracted increasing interest due to their unique inherent chirality and potential applications in next-generation optoelectronic and spintronic devices. However, COIP ferroelectrics are very sparse. In this work, for the first time, we present the nickel-nitrite ABX 3 COIP ferroelectrics, [( R and S )- N -fluoromethyl-3-quinuclidinol]Ni(NO 2 ) 3 ([( R and S )-FMQ]Ni(NO 2 ) 3 ), where the X-site is the rarely seen NO 2 - bridging ligand. [( R and S )-FMQ]Ni(NO 2 ) 3 display mirror-relationship in the crystal structure and vibrational circular dichroism signal. It is emphasized that [( R and S )-FMQ]Ni(NO 2 ) 3 show splendid ferroelectricity with both an extremely high phase-transition point of 405 K and a spontaneous polarization of 12 μC/cm 2 . To our knowledge, [( R and S )-FMQ]Ni(NO 2 ) 3 are the first examples of nickel-nitrite based COIP ferroelectrics. This finding expands the COIP family and throws light on exploration of high-performance COIP ferroelectrics.

Organic-inorganic ABX 3 (A, B = cations, X = anion) hybrids with perovskite structure have recently attracted tremendous interest due to their structural tunability and rich functional properties, such as ferroelectricity. However, ABX 3 hybrid ferroelectrics with other structures have rarely been reported. Here, we successfully designed an ABX 3 hybrid ferroelectric [(CH 3 ) 3 NCH 2 F]ZnCl 3 with a spontaneous polarization of 4.8 μC/cm 2 by the molecular modification of [(CH 3 ) 4 N]ZnCl 3 through hydrogen/halogen substitution. It is the first zinc halide ABX 3 ferroelectric, which contains one-dimensional [ZnCl 3 ] - n chains of corner-sharing ZnCl 4 tetrahedra, distinct from the anionic framework of corner-sharing or face-sharing BX 6 octahedra in the ABX 3 perovskites. From zero dimension to one dimension, the high symmetry of ZnCl 4 tetrahedra is broken, and all of them align along one direction to form a polar [ZnCl 3 ] - n chain, beneficial to the generation of ferroelectricity. This finding provides an efficient polar anionic framework for enriching the family of hybrid ferroelectrics by assembling with various cations and should inspire further exploration of new classes of organic-inorganic ABX 3 ferroelectrics.

The past decade has witnessed much progress in designing molecular ferroelectrics, whose intrinsic mechanical flexibility, structural tunability, and easy processability are desirable for next-generation flexible and wearable electronic devices. However, an obstacle in expanding their promising applications in nonvolatile memory elements, capacitors, and sensors is effectively modulating the Curie temperature ( T c ). Here, taking advantage of fluorine substitution on the reported molecular ferroelectric, (pyrrolidinium)MnCl 3 , we present enantiomeric perovskite ferroelectrics, namely, ( R) - and ( S) -3-(fluoropyrrolidinium)MnCl 3 . The close van der Waal's radii and the similar steric parameters between H and F atoms ensure the minimum disruption of the crystal structure, while their different electronegativity and polarizability can trigger significant changes in the physical and chemical properties. As expected, the T c gets successfully increased from 295 K in (pyrrolidinium)MnCl 3 to 333 K in these two homochiral compounds. Such a dramatic enhancement of 38 K signifies an important step toward designing high- T c molecular ferroelectrics. In the light of the conceptually new idea of fluorine substitution, one could look forward to a continuous succession of new molecular ferroelectric materials and technology developments.

Quasi-spherical molecules have recently been developed as promising building blocks for constructing high-performance molecular ferroelectrics. However, although the modification of spherical molecules into quasi-spherical ones can efficiently lower the crystal symmetry, it is still a challenge to precisely arouse a low-symmetric polar crystal structure. Here, by introducing directional hydrogen-bonding interactions in the molecular modification, we successfully reduced the cubic centrosymmetric Pm3̅ m space group of [quinuclidinium]ClO 4 at room temperature to the orthorhombic polar Pna2 1 space group of [3-oxoquinuclidinium]ClO 4 . Different from the substituent groups of -OH, -CH 3 , and ═CH 2 , the addition of a ═O group with H-acceptor to [quinuclidinium] + forms directionally N-H···O═C hydrogen-bonded chains, which plays a critical role in the generation of polar structure in [3-oxoquinuclidinium]ClO 4 . Systematic characterization indicates that [3-oxoquinuclidinium]ClO 4 is an excellent molecular ferroelectric with a high Curie temperature of 457 K, a large saturate polarization of 6.7 μC/cm 2 , and a multiaxial feature of 6 equiv ferroelectric axes. This work demonstrates that the strategy of combining quasi-spherical molecule building blocks with directional intermolecular interactions provides an efficient route to precisely design new eminent molecular ferroelectrics.

With the flourishing development of (CH 3 NH 3 )PbI 3 , three-dimensional (3D) organic-inorganic perovskites with unique structure-property flexibility have become a worldwide focus. However, they still face great challenges in effectively inducing ferroelectricity. Despite the typical 3D perovskite structure and the ability of dabco (1,4-diazabicyclo[2.2.2]octane) to trigger phase transition, unfortunately [H 2 dabco]RbCl 3 adopts a nonpolar crystal structure without ferroelectricity. Within the larger RbI 3 framework, we assemble N-methyl-1,4-diazoniabicyclo[2.2.2]octane (MeHdabco) obtained by reducing the molecular symmetry of dabco into a new 3D organic-inorganic perovskite. As expected, MeHdabco bearing a molecular dipole moment turns out to be vital in the generation of polar crystal structure and ferroelectric phase transition occurring at 430 K. It is the first time that the dabco component has been successfully wrapped into a 3D cage to achieve ferroelectricity even through there is intensive research on dabco. This precise molecular design strategy based on the modification of molecular symmetry provides an efficient route to enrich the family of 3D organic-inorganic perovskite ferroelectrics. Intriguingly, the iodine-doped crystal can exhibit intense saffron yellow luminescence with a high quantum yield of 17.17% under UV excitation, extending its application in the field of ferroelectric luminescence and/or multifunctional devices.

A novel concept to improve the catalytic functions of nucleic acids (DNAzymes) is introduced. The method involves the conjugation of a DNA recognition sequence (aptamer) to the catalytic DNAzyme, yielding a hybrid structure termed "nucleoapzyme". Concentrating the substrate within the "nucleoapzyme" leads to enhanced catalytic activity, displaying saturation kinetics. Different conjugation modes of the aptamer/DNAzyme units and the availability of different aptamer sequences for a substrate provide diverse means to design improved catalysts. This is exemplified with (i) The H2O2-mediated oxidation of dopamine to aminochrome using a series of hemin/G-quadruplex-dopamine aptamer nucleoapzymes. All nucleoapzymes reveal enhanced catalytic activities as compared to the separated DNAzyme/aptamer units, and the most active nucleoapzyme reveals a 20-fold enhanced activity. Molecular dynamics simulations provide rational assessment of the activity of the various nucleoapzymes. The hemin/G-quadruplex-aptamer nucleoapzyme also stimulates the chiroselective oxidation of L- vs D-DOPA by H2O2. (ii) The H2O2-mediated oxidation of N-hydroxy-L-arginine to L-citrulline by a series of hemin/G-quadruplex-arginine aptamer conjugated nucleoapzymes.

The Michael addition-elimination of ylide to alpha,beta-unsaturated imines leads to a highly diastereoselective and enantioselective synthesis of vinylcyclopropanecarbaldehydes in good to high yields for the first time. A sequential cyclopropanation-aziridination protocol for the preparation of cyclopropylaziridines is also developed with good diastereoselectivity in good to high yields.