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Metal–Organic Frameworks: Trapping and Releasing of Oxygen in Liquid by Metal–Organic Framework with Light and Heat (Small 22/2021)

  • First Published: 02 June 2021
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In article number 2004351, Ryotaro Matsuda and co-workers present a bifunctional MOF that exhibits activation of triplet oxygen into singlet oxygen under UV-light irradiation and the successive oxygen trapping in liquids, providing a paradigm shift in the field of gas adsorption in MOF nanospace from “gas-phase molecular adsorption” to “liquid-phase molecular adsorption.”

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Room Temperature Phosphorescence: Boosting Room Temperature Phosphorescence Performance by Alkyl Modification for Intravital Orthotopic Lung Tumor Imaging (Small 22/2021)

  • First Published: 02 June 2021
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In article number 2005449, Qiyun Tang, Yang Shi, Dan Ding, and co-workers report a simple short alkyl modified strategy to regulate the molecular aggregation state and remarkably improve the luminescent efficiency and phosphorescence lifetime of pure organic room temperature phosphorescence (RTP) materials. The crystalline nanoparticles of RTP molecules are prepared with a “Top-Down” method, which give excellent performance in phosphorescent bioimaging application.

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Carbon Dioxide Reduction: Modulation of Self-Assembly Enhances the Catalytic Activity of Iron Porphyrin for CO2 Reduction (Small 22/2021)

  • First Published: 02 June 2021
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In article number 2006150, Mio Kondo, Shigeyuki Masaoka, and co-workers demonstrate that the self-assembly of iron porphyrin complexes with space modulators affords the porous crystalline solid with hydrophobic pores and adjacent active sites. The material efficiently catalyzes electrochemical CO2 reduction in aqueous media.

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Solar Water Splitting: Hollow Multishelled Structured SrTiO3 with La/Rh Co-Doping for Enhanced Photocatalytic Water Splitting under Visible Light (Small 22/2021)

  • First Published: 02 June 2021
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In article number 2005345, Ranbo Yu, Dan Wang, and co-workers successfully incorporate the advanced structural design to construct the La- and Rh- co-doped SrTiO3 (STO:La/Rh) hollow multi-shelled structures (HoMSs). The elevated visible light responsive photocatalytic water splitting performances give a promising prospect for HoMSs-based materials in photocatalytic and photo related fields. With a broad vision, the authors foresee that the dawn of HoMSs photocatalyst is arriving with more innovative evolutions.

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Masthead: (Small 22/2021)

  • First Published: 02 June 2021

Guest Editorial

Essay

The “Chemistree” of Porous Coordination Networks: Taxonomic Classification of Porous Solids to Guide Crystal Engineering Studies

  • First Published: 10 March 2021
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A taxonomic approach to classification of porous solids, with particular emphasis upon porous coordination networks (PCNs), is detailed. The resulting “chemistree” can be used to enable top-down (from topology) or bottom-up (starting at an individual PCN) approaches to the crystal engineering of new families of PCNs for systematic structure/function studies.

Reviews

Incorporation of Active Metal Species in Crystalline Porous Materials for Highly Efficient Synergetic Catalysis

  • First Published: 05 November 2020
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Incorporation of active metal species in crystalline porous materials (CPMs) can synergize the respective strengths and allow them to collaborate with each other for synergistic catalysis. In this review, the state-of-the art progress in the encapsulation of catalytically active metal species by CPMs as well as their synergy functions for enhanced catalytic performance is summarized in detail.

MOFs-Derived Carbon-Based Metal Catalysts for Energy-Related Electrocatalysis

  • First Published: 18 January 2021
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Porous carbon materials for electrocatalysis have attracted explosive interests. In this review, the effects of synthesis strategy, coordination environment, morphology, and composition on the catalytic activity of metal–organic framework-derived carbon-based single atoms and metal nanoparticles catalysts for energy-related electrocatalysis are summarized, which are useful for developing high-efficient carbon-based metal electrocatalysts in the future.

2D Redox-Active Covalent Organic Frameworks for Supercapacitors: Design, Synthesis, and Challenges

  • First Published: 18 January 2021
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Redox-active covalent organic frameworks (COFs) with specific functional groups, ordered structures, and regular open channels are promising electroactive materials for supercapacitors (SCs). This review focuses on surveying the design principles, synthetic methods, and representative advances of redox-active COFs in SCs. Key challenges and future directions of 2D redox-active COFs in this field are proposed as well.

Calcium-Based Metal–Organic Frameworks and Their Potential Applications

  • First Published: 03 November 2020
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Metal–organic frameworks built on calcium (Ca-MOFs) represent an important subgroup of MOFs. They possess diverse structures, low toxicity, and light weight, and hold promise for a variety of applications. An overview on Ca-MOFs reported to date, including a summary of inorganic building units, organic ligands, crystal structures, porosity, and selected physical properties, as well as most promising applications is offered.

Nanoporous Metal Phosphonate Hybrid Materials as a Novel Platform for Emerging Applications: A Critical Review

  • First Published: 19 February 2021
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Nanoporous metal phosphonates have shown great potential in facilitating functionality, shapeability, combination, and miniaturization, which offer a multifunctional platform to make breakthroughs in many promising application fields, such as optics, electronics, ionics, membranes, and catalysis. All the recent developments in designing these porous metal phosphonates are summarized here with a special emphasis on the porosity-property-functionality relationships.

Rare-Earth-Based Metal–Organic Frameworks as Multifunctional Platforms for Catalytic Conversion

  • First Published: 19 February 2021
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The rare-earth (RE)-based metal–organic frameworks (MOFs) can exhibit good catalytic abilities for the cooperation of RE elements and porous MOF structures, and have been studied in many areas such as energy conversion, environmental governance, and organic synthesis. In this review, RE-MOFs for catalytic conversion are summarized for the first time.

Porous Noble Metal Electrocatalysts: Synthesis, Performance, and Development

  • First Published: 18 March 2021
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Porous noble metal is an inherently promising electrocatalysts and nowadays great efforts have been made to explore new efficient synthesis methods and establish structural–performance relationships. In this review, the very recent progress in strategies for preparing porous noble metal, including innovation and deeper understanding of traditional methods, as well as structure–activity relationships are summarized.

Recent Advances in Catalytic Confinement Effect within Micro/Meso-Porous Crystalline Materials

  • First Published: 16 March 2021
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The catalytic confinement effect aroused by the pore features of porous crystalline materials has triggered great interest in heterogeneous catalysis. This review provides a fundamental understanding regarding the concept of confinement effects and highlights the impact of confinement effects on diffusion, adsorption/desorption, and catalytic reaction in zeolites, carbon nanotubes, and metal–organic frameworks.

Applications of MOFs as Luminescent Sensors for Environmental Pollutants

  • First Published: 26 February 2021
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Luminescent MOFs have attracted remarkable attention to detect environmental pollutants because of their excellent selectivity, sensitivity, and recyclability. In this review, the sensing mechanisms and construction principles of luminescent MOFs are discussed, and the state-of-the-art luminescent MOF-based sensors of environmental pollutants, including pesticides, antibiotics, explosives, VOCs, toxic gas, toxic small molecules, radioactive ions, and heavy metal ions are highlighted.

Crystalline Multi-Metallic Compounds as Host Materials in Cathode for Lithium–Sulfur Batteries

  • First Published: 10 March 2021
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Crystalline multi-metal compounds such as transition metal composite oxides, binary metal chalcogenides, double or complex salts, etc. as host materials, can provide strong interaction with polysulfides and high catalytic ability for transfer of polysulfides. This is a promising approach to answer the main problems of sulfur cathode to achieve a better lithium–sulfur battery.

Recent Advances on Conductive 2D Covalent Organic Frameworks

  • First Published: 24 February 2021
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2D covalent organic frameworks (2D-COFs) with high intrinsic electrical conductivities, extended conjugated π-systems, and well-defined porous networks are important members of the 2D materials family. This review highlights the topology and morphology controls of conductive 2D-COFs, and outlines their applications in field-effect transistors, photodetectors, sensors, catalysis, and energy storage.

Three-Dimensional Graphene-Based Macrostructures for Electrocatalysis

  • First Published: 18 March 2021
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The latest progress of 3D graphene-based macrostructures is discussed systematically to promote the exploration of high-efficiency electrocatalysts for energy storage and conversion. Materials preparation and functional modification are first introduced followed by their electrocatalytic performance for important electrochemical energy conversion reactions. Key issues are analyzed to guide the further research in future.

Control of Proton-Conductive Behavior with Nanoenvironment within Metal–Organic Materials

  • First Published: 18 March 2021
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The high crystallinity and designability of metal–organic materials (MOMs) make them advantageous over conventional noncrystalline counterparts. This review summarizes and examines the fundamental principles and various design strategies of proton-conductive MOMs, and sheds light on the nanoconfinement effects and the importance of hydrophobicity on specific occasions, which have been often disregarded. Besides, challenges and future prospects are presented.

Advances in Chiral Metal–Organic and Covalent Organic Frameworks for Asymmetric Catalysis

  • First Published: 18 March 2021
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Chiral metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) represent attractive and promising heterogeneous asymmetric catalysts for a wide range of organic transformations. This review provides a comprehensive overview of the developments of asymmetric catalysis by chiral MOF and COF catalysts with emphasis on their syntheses, structures, and asymmetric catalytic performance.

Metal–Organic Frameworks and Their Derivatives: Designing Principles and Advances toward Advanced Cathode Materials for Alkali Metal Ion Batteries

  • First Published: 18 March 2021
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Metal–organic frameworks (MOFs) bring a new light to the development of cathode materials owing to their unique and designable porous structures and components. Here, the research advances on MOF-related cathode materials in alkali metal ion batteries are summarized in terms of structure design, composite fabrication, and morphology engineering, providing a comprehensive guidance on designing high-performance MOF-related cathode materials.

Crystalline Porous Materials for Nonlinear Optics

  • First Published: 18 March 2021
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In this review, the nonlinear optical properties and applications of crystalline porous materials, including MOFs, COFs, and POMs, are summarized. Such a summary will provide guidelines for the design of crystalline porous materials for nonlinear optics, not only from a basic perspective but also in terms of applications.

Communications

Hollow Multishelled Structured SrTiO3 with La/Rh Co-Doping for Enhanced Photocatalytic Water Splitting under Visible Light

  • First Published: 19 January 2021
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Successfully co-doping of La and Rh into SrTiO3 hollow multishelled structures (STO:La/Rh HoMSs) expands the light absorption edge of SrTiO3 HoMSs from 380 to 520 nm. The unique hierarchical hollow multishelled structure and relatively thin shells further elevate the visible-light-harvesting and charge separation abilities for STO:La/Rh HoMSs, showing boosted photocatalytic water splitting performances.

Design of Hybrid Zeolitic Imidazolate Framework-Derived Material with C–Mo–S Triatomic Coordination for Electrochemical Oxygen Reduction

  • First Published: 28 July 2020
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A well-defined Mo-based heterostructured electrocatalyst is synthesized and used as a model system for examining the correlation of interface charge perturbation with oxygen reduction reaction (ORR) performance. This work unveils that the appropriate electronic steering at the atomic-level coupled C-Mo-S interface is responsible for the enhanced ORR activity, which will shed light on future design of efficient electrocatalysts.

Frontispiece

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Molecular Recognition: Multipoint Hydrogen Bonding-Based Molecular Recognition of Amino Acids and Peptide Derivatives in a Porous Metal-Macrocycle Framework: Residue-Specificity, Diastereoselectivity, and Conformational Control (Small 22/2021)

  • First Published: 02 June 2021
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In article number 2005803, Shohei Tashiro, Mitsuhiko Shionoya, and co-workers report residue-specific recognition of amino acids and peptide derivatives in a porous metal-macrocycle framework. Among several amino acid residues, serine moieties are site- and diastereo-selectively adsorbed to a certain binding site on the pore surface through multipoint hydrogen bonding as clearly visualized by single-crystal X-ray diffraction analysis.

Communications

Multipoint Hydrogen Bonding-Based Molecular Recognition of Amino Acids and Peptide Derivatives in a Porous Metal-Macrocycle Framework: Residue-Specificity, Diastereoselectivity, and Conformational Control

  • First Published: 18 February 2021
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Amino acid and peptide derivatives are site-selectively recognized in a porous metal-macrocycle framework through multiple hydrogen bonding. Serine residues are diastereoselectively and residue-specifically adsorbed on the pore-surface through multiple hydrogen bonds. In addition, conformation of a peptide adsorbed on the pore-surface is highly controlled to adopt a poly-l-proline type I helix-like structure.

Encapsulating Copper Nanocrystals into Metal–Organic Frameworks for Cascade Reactions by Photothermal Catalysis

  • First Published: 18 January 2021
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In this work, the oriented growth of HKUST-1 on Cu2O nanocrystals (NCs) in a one-to-one structure has been successfully fabricated by precisely controlling the rates between metal oxide etching and HKUST-1 formation. Upon reduction of Cu2O to Cu NCs, the obtained Cu@HKUST-1 exhibits synergistically enhanced catalytic performance toward the cascade reactions under mild conditions involving visible-light irradiation.

Full Papers

Trapping and Releasing of Oxygen in Liquid by Metal–Organic Framework with Light and Heat

  • First Published: 02 November 2020
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A bifunctional metal–organic framework (MOMF-1) exhibits on-demand activation of triplet oxygen into singlet oxygen under ultraviolet-light irradiation and the successive trapping of them into its framework to form MOMF-2 in liquids. Moreover, MOMF-2 can release trapped oxygen and returns to MOMF-1 quantitatively upon heating in which the structural integrity is maintained.

Boosting Room Temperature Phosphorescence Performance by Alkyl Modification for Intravital Orthotopic Lung Tumor Imaging

  • First Published: 18 February 2021
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Regulating molecular aggregation to improve the luminescent efficiency and room temperature phosphorescence lifetime is demonstrated by a simple alkyl modification strategy. The resultant crystalline nanoparticles can selectively light up orthotopic lung tumors via room temperature phosphorescence after intravenous administration into pulmonary metastatic carcinoma-bearing mice, showing a rather high signal-to-background ratio of 65.

Modulation of Self-Assembly Enhances the Catalytic Activity of Iron Porphyrin for CO2 Reduction

  • First Published: 09 March 2021
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The self-assembly of iron-porphyrin complexes bearing bulky substituents with intermolecular interaction ability (“space modulators”) affords crystalline solids with adjacent catalytically active sites and hydrophobic pores. The crystalline solid can catalyze the CO2 reduction reaction to produce CO under electrochemical conditions in aqueous media. The present study provides a novel approach to construct porous crystalline solids for small-molecule conversions.

Frontispiece

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Sugar Conversion: Incorporation of Al3+ Sites on Brønsted Acid Metal–Organic Frameworks for Glucose-to-Hydroxylmethylfurfural Transformation (Small 22/2021)

  • First Published: 02 June 2021
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5-hydroxylmethylfurfural (HMF) is a value-added chemical obtained from sugars including glucose. In article number 2006541, Satoshi Horike, Kanokwan Kongpatpanich, and co-workers design a metal–organic framework (MOF) catalyst for glucose-to-HMF transformation by incorporation of Lewis Al3+ site to Brønsted sulfonated MOFs. The local structure of acid sites is elucidated by XANES and DFT calculations.

Full Papers

Incorporation of Al3+ Sites on Brønsted Acid Metal–Organic Frameworks for Glucose-to-Hydroxylmethylfurfural Transformation

  • First Published: 18 March 2021
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Lewis Al3+ sites have been incorporated into Brønsted sulfonated MOFs to promote glucose conversion to 5-hydroxylmethylfurfural, which is a value-added chemical obtained from sugars. The local structure of acid sites has been elucidated by X-ray absorption near-edge structure (XANES) combined with density functional theory calculations.

Frontispiece

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Covalent–Organic Frameworks: Single-Pore versus Dual-Pore Bipyridine-Based Covalent–Organic Frameworks: An Insight into the Heterogeneous Catalytic Activity for Selective CH Functionalization (Small 22/2021)

  • First Published: 02 June 2021
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Transition metal catalyzed carbon—hydrogen functionalization imparts a paradigm shift in the complex target synthesis, including pharmaceutical and material science applications. To establish structure-function-property relationship of covalent organic frameworks, palladium docked dual-pore COFs with controllable bipyridine content exhibit regioselective C—H to C—X (X = Cl, Br, I) and C—O functionalization, and compared with single pore framework. This protocol presented by Shengqian Ma and co-workers (article number 2003970) features high efficiency, remarkable reusability, and recyclability.

Full Papers

Single-Pore versus Dual-Pore Bipyridine-Based Covalent–Organic Frameworks: An Insight into the Heterogeneous Catalytic Activity for Selective CH Functionalization

  • First Published: 11 September 2020
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Metal-catalyzed functionalization of sp2 and sp3 carbonhydrogen bond is very appealing for pharmaceutical industry. Immobilization of palladium is critical to optimize the catalytic activity of covalent organic frameworks with recyclability and reusability. This article illustrates the structure–functional relationship of palladium decorated dual-pore and single-pore covalent–organic frameworks through regioselective carbonhydrogen to carbonchlorine, carbonbromine, and carbonoxygen functionalization.

Confined Thermolysis for Oriented N-Doped Carbon Supported Pd toward Stable Catalytic and Energy Storage Applications

  • First Published: 30 July 2020
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An N-doped oriented carbon-structured (fiber-like) composite with hierarchical pore and ultrafine Pd nanoclusters is fabricated by simultaneously taking advantage of the confined pyrolysis strategy and disparate bond environments within metal–organic frameworks (MOFs). The synthesized composite Pd@NDHPC@mSiO2 manifests extremely high catalytic activity toward tandem catalysis and much boosted cycling stability in Li–S batteries.

Tunable Metal–Organic Frameworks Based on 8-Connected Metal Trimers for High Ethane Uptake

  • First Published: 25 August 2020
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A series of open-metal-site-free metal–organic frameworks (MOFs) based on 8-connected metal trimers is developed by using a synthetic strategy called angle bending modulation. Despite the absence of open metal sites as binding sites, these materials exhibit excellent ethane uptake capacity and high inverse C2H6/C2H4 separation selectivity.

Construction of Donor–Acceptor Heterojunctions in Covalent Organic Framework for Enhanced CO2 Electroreduction

  • First Published: 05 November 2020
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A donor–acceptor heterojunctions is constructed in cobalt porphyrin-based COF (TT-Por(Co)-COF) to enhance the current density of CO2 electroreduction reaction due to its favorable charge transfer capability. TT-Por(Co)-COF nanosheets show a high FECO of 91.4% at −0.6 V versus reversible hydrogen electrode (RHE) and large partial current density of 7.28 mA cm−2 at −0.7 V versus RHE in aqueous solution.

High-Performance Lithium-Ion Capacitors Based on Porosity-Regulated Zirconium Metal−Organic Frameworks

  • First Published: 03 December 2020
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Hierarchical nanoporous Zr-MOF (metal−organic framework) has been designed as the anode of hybrid lithium-ion capacitors (HLICs) with well-organized porosity for fast Li+ ion diffusion and multiple active sites for Li+ ion interaction. The HLICs utilizing Zr-MOF as pseudocapacitive anode and active carbon as cathode exhibit high energy density, large power density, and long-term cyclability.

In Situ Porphyrin Substitution in a Zr(IV)-MOF for Stability Enhancement and Photocatalytic CO2 Reduction

  • First Published: 22 February 2021
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The in situ porphyrin substitution strategy is developed for modifying labile interpenetrated BUT-109(Zr), affording BUT-110 with enhanced chemical stability and photocatalytic activity. By tuning the species and contents of metalloporphyrin in BUT-110, some of the BUT-110 MOFs may serve as potential photocatalysts for selective CO2-to-CO reduction, in the absence of photosensitizer.

3D Thioether-Based Covalent Organic Frameworks for Selective and Efficient Mercury Removal

  • First Published: 19 February 2021
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3D thioether-based COFs, JUC-570 and JUC-571, are for the first time prepared by the bottom-up approach, and used for mercury (Hg2+) removal from aqueous solution. In particular, JUC-570 is periodically decorated with isopropyl groups around imine bonds, which displays higher chemical stability, BET specific surface area, and Hg2+ removal performance.

Engineering Elastic Properties of Isostructural Molecular Perovskite Ferroelectrics via B-Site Substitution

  • First Published: 14 March 2021
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Elastic properties of two isostructural molecular perovskite ferroelectrics are systematically investigated. Strikingly, MDABCO-KI3 shows much higher moduli than those of MDABCO-NH4I3 due to the marked different strengths between KI coordination bonds and NH4…I hydrogen interactions. This work demonstrates that it is possible to manage elastic properties of molecular ferroelectrics via facile chemical substitution.