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We probed the solid-state formation of gold nanoparticles through mechanochemically-activated aging. The acquired data allowed for the establishment of the first kinetic model for solid-state nanoparticle formation.

Resonant acoustic mixing (RAM) enables mechanochemical synthesis without milling media or bulk solvents.

We use a gold nanoparticle synthesis as a model system to study the morphological and compositional changes in gold(III) precursor particles, while reduction is taking place during aging after mechanical activation. Scanning transmission electron microscopy coupled with a high-angle annular dark field detector revealed the nanoscale changes in particle morphology, while electron energy loss spectroscopy mapped the changes in the chemical landscape during the reduction process. Tracking a specific region of interest on the sample grid allowed for comparisons to be made of the same particles across a two day monitoring period. High-angle annular dark field images permitted the visualization of particle size reduction of the gold salt while electron energy loss spectroscopy captured the surprising mobility of the lighter chlorine and sodium ions in a solid matrix during the reduction process. This system offers unique insight into precursor particle reactivity in the solid phase, which is relevant for many mechanochemical and aging-based reactions.

Organic room-temperature phosphorescence, a spin-forbidden radiative process, has emerged as an interesting but rare phenomenon with multiple potential applications in optoelectronic devices, biosensing, and anticounterfeiting. Covalent organic frameworks (COFs) with accessible nanoscale porosity and precisely engineered topology can offer unique benefits in the design of phosphorescent materials, which are presently unexplored. Here, we report an original approach of covalent doping, whereby a bi-component COF is synthesized by copolymerization of halogenated and unsubstituted phenyldiboronic acids, allowing for random distribution of functionalized units at varying ratios, yielding highly phosphorescent COFs. Such controlled halogen doping enhances the intersystem crossing while minimizing the triplet-triplet annihilation by diluting the phosphors. The rigidity of the COF suppresses vibrational relaxation and allows high phosphorescence quantum yield (Φ(phos)

Luminescent metal–organic frameworks (MOFs) are of interest for sensing, theranostics, dosimetry, and other applications. The use of lanthanoids in MOF metal nodes allows for intrinsic met-al-based luminescence. In this work, a facile route for modulat-ing the photoluminescent and radioluminescent properties of Tb(III)-based MOFs is reported. By using Tb(III)-cluster nodes as X-ray attenuators, and organic linkers with varying excited state energies as sensitizers, MOFs with metal-based, linker-based, and metal+linker-based photo- and radioluminescence are reported.

Applying Szilágyi's procedure for the SACS process using aqueous solutions resulted in the formation of the metal oxide particles. However, by using DMF, mixed-metal MIL-101 was successfully obtained.

Hybrid rocket propulsion can contribute to reduce launch costs by simplifying engine design and operation. Hypergolic propellants, i.e. igniting spontaneously and immediately upon contact between fuel and oxidizer, further simplify system integration by removing the need for an ignition system. Such hybrid engines could also replace currently popular hypergolic propulsion approaches based on extremely toxic and carcinogenic hydrazines. Here we present the first demonstration for the use of hypergolic metal-organic frameworks (HMOFs) as additives to trigger hypergolic ignition in conventional paraffin-based hybrid engine fuels. HMOFS are a recently introduced class of stable and safe hypergolic materials, used here as a platform to bring readily tunable ignition and combustion properties to hydrocarbon fuels. We present an experimental investigation of the ignition delay (ID, the time from first contact with an oxidizer to ignition) of blends of HMOFs with paraffin, using White Fuming Nitric Acid (WFNA) as the oxidizer. The majority of measured IDs are under 10 ms, significantly below the upper limit of 50 ms required for functional hypergolic propellant, and within the ultrafast ignition range. A theoretical analysis of the performance of HMOFs-containing fuels in a hybrid launcher engine scenario also reveals the effect of the HMOF mass fraction on the specific impulse (Isp) and density impulse (ρIsp). The use of HMOFs to produce paraffin-based hypergolic fuels results in a slight decrease of the Isp and ρIsp compared to that of pure paraffin, similar to the effect observed with Ammonia Borane (AB), a popular hypergolic additive. HMOFs however have a much higher thermal stability, allowing for convenient mixing with hot liquid paraffin, making the manufacturing processes simpler and safer compared to other hypergolic additives such as AB.

The rectangular tetratopic linker, 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) along with rare-earth (RE) ions is used for the synthesis of 9 isostructures of a metal–organic framework (MOF) with shp topology, named RE-CU-10 (RE = Y(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III) and Lu(III)). The synthesis of each RE-CU-10 analogue requires different reaction conditions to achieve high quality phase pure products. Single crystal X-ray diffraction indicates the presence of a RE9-cluster in Y- to Tm-CU-10, while a unique RE11-cluster is observed for Yb- and Lu-CU-10. The photooxi-dation performance of the reported RE-CU-10 analogues is evaluated, giving insight into the competitive process of ligand-to-metal energy transfer versus the generation of singlet oxygen by RE-CU-10. The singlet oxygen produced is used to detoxify a mustard gas simulant 2-chloroethylethyl sulfide (2-CEES) to 2-chloroethyl ethyl sulfoxide (2-CEESO), with half-lives ranging from 4.0 to 5.8 min, some of the fastest reported to date using UV-irradiation and < 1 mol% catalyst, in methanol under O2 saturation.

A simple mechanochemical strategy provides a mild, straightforward, and rapid route to convert gold metal into organosoluble Au(iii) salts, which can be readily used as precursors for Au(i) salts and gold nanoparticles.

Resonant acoustic mixing (RAM) offers a simple, efficient route for mechanochemical synthesis in the absence of milling media or bulk solvents. Here, we show the use of RAM to conduct the copper-catalysed coupling of sulfonamides and carbodiimides. This coupling was previously reported to take place only by mechanochemical ball milling, while in conventional solution environments it is not efficient, or does not take place at all. The results demonstrate RAM as a suitable methodology to conduct reactions previously accessed only by ball milling and provide a detailed, systematic overview of how the amount of liquid additive, measured by the ratio of liquid volume to weight of reactants (

Previously unreported, luminescent polymorphs and solid solutions of a simple gold(i) salt, accessed through heating and mechanochemistry.

We report the first X-ray single crystal structures of hypochlorite (ClO- ) and hypobromite (BrO- ) salts, including hydrated sodium hypochlorite, a staple of the chlorine industry and ubiquitous bleaching and disinfection agent for almost 200 years. The structures, supported by variable-temperature Raman spectroscopy on individual crystals and periodic density-functional theory (DFT) calculations, provide insight into solid-state geometry and supramolecular chemistry of hypohalite ions.

We present SpeedMixing, a rapid blending technology, as an approach for fast mechanosynthesis and discovery of model pharmaceutical cocrystals through rapid spinning in the absence of bulk solvents and milling/grinding media. Syntheses of pharmaceutical cocrystals based on the active pharmaceutical ingredients (APIs) carbamazepine, dihydrocarbamazepine, and nicotinamide demonstrate SpeedMixing as a method for rapid, scalable, as well as controllable and selective synthesis of cocrystals, cocrystal polymorphs and stoichiomorphs, including the discovery of an unexpected methanol solvate of the archetypal cocrystal of carbamazepine and saccharin, which has eluded extensive screens over 20 years.

In this study, we report the polymorphism of six coordinated Sn(IV)- tetrabromophenyl porphyrins axially armed with fluorine-substituted phenolate ligands (structural formula [Sn(TBrPP)

We report a comparative study of two structurally similar donor–acceptor complexes with (1a) and without (2a) H-bonding using X-ray crystallography, spectroscopic analysis, and density functional t...

We provide a Cambridge Structural Database (CSD) analysis of the role of halogen bonds and halogen···halogen interactions in the solid-state structures of porphyrins. This survey provides a detaile...

A series of new halogenated bis(acenaphthylene)dione (BAN) derivatives was synthesized, and the effect of halogen bonding on both molecular and crystal structure, and charge transport in n-type thin film transistors was investigated.

We present a new class of anionic metallohelicates based on an abundant, industrially relevant salicylic acid derivative, leading to discrete double and triple-stranded architectures based on divalent and trivalent metals (Cu2+, Fe3+, respectively). The ability to assemble the metallohelicates in a solvent-free environment presents the opportunity to develop an inexpensive and environmentally-friendly design of helicate materials.

Mechanochemistry enables rapid access to boron imidazolate frameworks (BIFs), including ultralight materials based on Li and Cu(i) nodes, as well as new, previously unexplored systems based on Ag(i) nodes. Compared to solution methods, mechanochemistry is faster, provides materials with improved porosity, and replaces harsh reactants (e.g. n-butylithium) with simpler and safer oxides, carbonates or hydroxides. Periodic density-functional theory (DFT) calculations on polymorphic pairs of BIFs based on Li+, Cu+ and Ag+ nodes reveals that heavy-atom nodes increase the stability of the open SOD-framework relative to the non-porous dia-polymorph., Mechanochemistry enables rapid access to boron imidazolate frameworks (BIFs), including ultralight materials based on Li and Cu(i) nodes, as well as new, previously unexplored systems based on Ag(i) nodes.

First-principles crystal structure prediction (CSP) is the most powerful approach for materials discovery, enabling the prediction and evaluation of properties of new solid phases based only on a diagram of their underlying components. Here, we present the first CSP-based discovery of metal-organic frameworks (MOFs), offering a broader alternative to conventional techniques which rely on geometry, intuition and experimental screening. Phase landscapes were calculated for three systems involving flexible Cu(II) nodes, which could adopt a potentially limitless number of network topologies and are not amenable to conventional MOF design. The CSP procedure was validated experimentally, through synthesis of materials whose structures perfectly matched those found among the lowest energy calculated structures, and whose relevant properties, such as combustion energies, could immediately be evaluated from CSP-derived structures.

A non-stoichiometric approach to control the solid-state behavior of protic ionic liquids (PILs) was demonstrated by direct mixing of 4,5-dicyanoimidazole (HDCNim) with either 1-ethylimidazole (C2i...

Chemical science 11(9), 2350 - 2355 (2020). doi:10.1039/C9SC06224F, Using the mechanosynthesis of the calcium urea phosphate fertilizer cocrystal as a model, we provide a quantitative investigation of chemical autocatalysis in a mechanochemical reaction. The application of in situ Raman spectroscopy and synchrotron X-ray powder diffraction to monitor the reaction of urea phosphate and either calcium hydroxide or carbonate enabled the first quantitative and in situ study of a mechanochemical system in which one of the products of a chemical reaction (water) mediates the rate of transformation and underpins positive feedback kinetics. The herein observed autocatalysis by water generated in the reaction enables reaction acceleration at amounts that are up to 3 orders of magnitude smaller than in a typical liquid-assisted mechanochemical reaction., Published by RSC, Cambridge

We present a new methodology for real-time observation of mechanochemical transformations, based on a magnetic resonance method in which T1-T2* relaxation time correlation maps are used to track the formation of the popular metal-organic framework (MOF) materials Zn-MOF-74 and ZIF-8. This two-dimensional (2D) relaxation correlation measurement is a new method utilizing simple saturation recovery to obtain a T1-T2* spectrum representing different hydrogen environments. The 2D T1-T2* results show a change in signal amplitudes, and their coordinates, within the plots as the reaction progresses, confirming reaction completion. Static solid samples are usually considered difficult to measure because of their short-lived T2* signal and their common non-exponential decay. Using a new processing method, the signal from samples with non-exponential decay was quantified. The importance of key parameters such as the instrument deadtime, the recovery times, and magnetic field strength for the measurement of solids with a short-lived signal is established. This novel magnetic resonance measurement is important since it provides a simple and easy way to analyse an entire solid reaction mixture within its reaction vessel.

We report a hexameric supramolecular cage assembled from the components of a Wittig-type phosphonium salt, held together by charge-assisted R-Br· · ·Br-· · ·Br-R halogen bonds. The cage reliably encapsulates small polar molecules, including aldehydes and ketones, to provide host-guest systems in which components are pre-formulated in a near-ideal stoichiometry for a base-activated Wittig olefination in the solid-state. These pre-formulated solids enable a molecular-level “baking powder” approach for solvent-free Wittig reactions, based on a design of solid-state reactivity in which the host for molecular inclusion also acts as a complementary reagent for the chemical transformation of an array of guests. These host-guest solid-state complexes can also act as supramolecular surrogates to their Wittig olefination vinylbromide products, in a Sonogashira-type coupling that enables one-pot mechanochemical conversion of an aldehyde to an enediyne.

We demonstrate the unprecedented ability to induce hypergolic behavior, i.e. rapid and spontaneous ignition upon contact with an oxidizer, in non-hypergolic metal fuels by blending them with hypergolic metal-organic frameworks (HMOFs). Using magnesium, aluminum or zinc metal as the fuel, we demonstrate materials with ignition delays (IDs) below 50 ms, and calculated specific impulse (Isp) in the 220-250 s range. These parameters are comparable to those of toxic and carcinogenic hydrazine-based hypergols conventionally used in aerospace technologies, suggesting a route to develop cleaner, safer propulsion systems.

Postsynthetic modification of metal-organic frameworks (MOFs) is an important strategy for accessing MOF analogues that cannot be easily synthesized de novo. In this work, the rare-earth (RE) cluster-based MOF Y-CU-10 with shp topology was modified through transmetalation using a series of RE ions, including La(III), Nd(III), Eu(III), Tb(III), Er(III), Tm(III), and Yb(III). In all cases, metal exchange higher than 70% was observed, with reproducible results. All transmetalated materials were fully characterized and compared to the parent MOF Y-CU-10 with regard to crystallinity, surface area, and morphology. Additionally, single-crystal X-ray diffraction measurements were performed to provide further evidence of transmetalation occurring in the nonanuclear cluster nodes of the MOF.

Organic room temperature phosphorescent (ORTP) compounds have recently emerged as a promising class of emissive materials with a multitude of potential applications. However, the number of building blocks that give rise to efficient ORTP materials is still limited, and the rules for engineering phosphorescent properties in organic solids are not well understood. Here, we report ORTP in a series of N-substituted acridone derivatives with electron-donating, electron-withdrawing, and sterically bulky substituents. X-ray crystallography shows that the solid-state packing varies progressively between coparallel and antiparallel π-stacking and separated π-dimers, depending on the size of the substituent. The detailed photophysical studies supported by DFT calculations reveal complex dynamics of singlet and triplet excited states, depending on the electronic effects of substituents and solid-state packing. The programmable molecular packing provides a lever to control the triplet-triplet annihilation that is manifested as delayed fluorescence in acridone derivatives with continuous (both parallel and antiparallel) π-stacking.

We demonstrate a co-crystal-based strategy to create new solid hypergols, that is, materials exhibiting spontaneous ignition when in contact with an oxidant, from typically non-hypergolic fuel molecules. In these materials, the energy content and density can be changed without affecting the ignition delay. The use of an imidazole-substituted decaborane as a hypergolic "trigger" component in combination with energy-rich but non-hypergolic nitrobenzene or pyrazine yielded hypergolic co-crystals that combine improved combustion properties with ultrashort ignition delays as low as 1 ms.

We knew what we had, but we never thought we would lose Professor Israel Goldberg, legendary crystallographer, professor, mentor, and friend. This virtual special issue (VSI) in Crystal Growth & Design is dedicated to the memory of Professor Israel Goldberg who passed on February 18, 2018, and serves as a homage to his long-standing career in crystallography, crystal engineering, and solid-state supramolecular chemistry and their applications.

Systematic investigation of combustion energies for popular metal–organic framework materials reveals energy content comparable to conventional energetic materials, which can be further modified an...

We demonstrate the use of ball milling mechanochemistry for rapid, simple, and materials-efficient synthesis of the organic mineral paceite CaCu(OAc)4·6H2O (where OAc- is the acetate ion), composed of coordination polymer chains containing alternating Ca2+ and Cu2+ ions, as well as its cadmium-based analogue CaCd(OAc)4·6H2O. While the synthesis of paceite in aqueous solutions requires a high excess of the copper precursor, mechanochemistry permits the use of stoichiometric amounts of reagents, as well as the use of poorly soluble and readily accessible calcium carbonate or hydroxide reactants. As established by thermochemical measurements, enthalpies of formation of both synthetic paceite and its cadmium analogue relevant to the mechanochemical reactions are highly exothermic. Reactions can also be conducted using accelerated aging, a synthetic technique that mimics geological processes of mineral weathering. Accelerated aging reactivity involving copper(II) acetate monohydrate (hoganite) and calcium carbonate (calcite) provides a potential explanation of how complex organic minerals like paceite could form in a geological environment.

The syntheses of some new zinc(II), palladium(II), platinum(II), ruthenium(II), rhodium(III) and silver(I) complexes of kojic acid (Hka) in both the absence and the presence of N,N- (2,2′-bipyridyl) and P- (triphenylphosphine) ligands are reported. The X-ray crystal structure of the mixed-ligand complex, [Ag(ka)(PPh3)], has been determined. It has been crystallized in a monoclinic lattice with space group symmetry P21/n. The molecular structures of the complexes are discussed on the basis of their IR, NMR (1H, 13C, 31P), UV-Vis, and EI and maldi-mass spectra, elemental analyses, molar conductivities and TGA behaviour. Kojic acid coordinates to the central metal ions in a mono-negative bidentate fashion through the carbonyl O- and the deprotonated ring hydroxy-O atoms. The in vitro anticancer activities of several of the complexes have been examined against the human ovarian cancer (VC-8-BRCA & VC-8) cell lines. The IC50 values for cell growth proliferation of [Ag(ka)(PPh3)] are 8.80 and 8.87 μM, respectively. The corresponding IC50 values for cisplatin are 9.12 and 10.07 μM. The DNA-binding properties of some of the complexes have been studied using UV-vis spectroscopy. The results indicate that the complexes may undergo intercalative CT-DNA binding in view of their hypochromism. The binding constants (Kb) of the complexes with CT-DNA show low-to-moderate binding abilities, which may result from steric hindrance around the metal ions from the primary chelate (Hka) or the bulky secondary (bpy, PPh3) moieties.

Location controlled symmetry reduction of the tetracarboxy porphyrin linker by altering the position of the coordinating groups leads to the design of a novel reduced symmetry linker 5,15-bis(p-carboxyphenyl)-10,20-bis(m-carboxyphenyl)porphyrin (H4-TpmCPP). The corresponding crystalline coordination framework Gd-TpmCMPF was synthesized by employing the NaOH modulator approach. The resulting compound is an 8-connected network with a bcu topology and two different perforated 1D channels. The consequence of reduced symmetry is highlighted in the geometry of capsular void spaces formed between porphyrin moieties in the framework which allows coordination with formate ions in the reaction mixture.

We report the first single crystal structures of hypochlorite and hypobromite salts, including hydrated sodium hypochlorite - a ubiquitous bleaching and disinfection agent in use for almost 200 years. The structures represent the first characterization of fundamentally important hypochlorite and hypobromite anions in the solid state, by X-ray crystallography and are supported by Raman spectroscopy on individual crystals. The structural analysis provides insight into supramolecular chemistry of the hypohalite ions in the hydrated environment of the NaOCl.5H2O and NaOBr.5H2O solid salts, and reveals measured Cl-O and Br-O bond lengths of 1.69 A and 1.82 A, respectively, which are significantly longer than those for corresponding higher-valence oxoanions, and in agreement with the values spectroscopically determined for hypohalous acids and corresponding oxides in the gas phase.

Rare-earth (RE) analogues of UiO-66 with non-functionalised 1,4-benzenedicarboxylate linkers are synthesised for the first time, and a series of synthetic approaches is provided to troubleshoot the synthesis. RE-UiO-66 analogues are fully characterised, and demonstrate a high degree of crystallinity, high surface area and thermal stability, consistent with the UiO-66 archetype.

Post-synthetic modification (PSM) of metal–organic frameworks (MOFs) is an important strategy for accessing MOF analogues that cannot be easily synthesized de novo. In this work, the rare-earth (RE) cluster-based MOF, Y-CU-10, with shp topology was modified through transmetallation using a series of RE ions, including: La(III), Nd(III), Eu(III), Tb(III), Er(III), Tm(III), and Yb(III). In all cases, metal-exchange higher than 70 % was observed, with reproducible results. All transmetallated materials were fully characterized and compared to the parent MOF, Y-CU-10, in regards to crystallinity, surface area, and morphology. Additionally, single-crystal X-ray diffraction (SCXRD) measurements were performed to provide further evidence of transmetallation occurring in the nonanuclear cluster nodes of the MOF.

Cocrystallisation of a fluorinated azobenzene with volatile cocrystal components dioxane or pyrazine yields halogen-bonded cocrystals that can be cut, carved or engraved with low-powered visible laser light. This process, termed cocrystal laser micro-shaping (CLMS), is enabled by cocrystallisation of a visible light dye with a volatile component, giving rise to materials that can be selectively disassembled with micrometer precision using gentle, non-burning irradiation in a commercial confocal microscope setup. The ability to shape and even machine cocrystals in 3D using laser powers between 0.5 and 20 mW, which are 2-4 orders of magnitude lower compared to laser powers used for machining metals, ceramics or polymers, is rationalized by CLMS targeting the disruption of weak supramolecular interactions between cocrystal components, rather than the breaking of covalent bonds in polymers or disruption of ionic structures required for conventional laser beam or focused ion beam machining processes, mainly by high-power laser heating.

Metal–organic frameworks (MOFs) are traditionally synthesized using formamide solvents that are hazardous to human health and the environment. In order to alleviate the environmental impact of MOF synthesis in both academic and industrial settings, safer and greener solvent alternatives are desired. Herein, STEPOSOL® MET-10U (N,N-dimethyl-9-decenamide), a bioderived solvent produced via olefin metathesis using renewable feedstocks, such as plant oils, is explored as a solvent for the synthesis of a series of structurally diverse MOFs.

Rare-earth (RE) analogues of UiO-66 with non-functionalised 1,4-benzenedicarboxylate linkers are synthesised for the first time, and a series of synthetic approaches is provided to troubleshoot the synthesis. RE-UiO-66 analogues are fully characterised, and demonstrate a high degree of crystallinity, high surface area and thermal stability, consistent with the UiO-66 archetype.

Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium acetate ([C2mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C2mim] n [{Ln2(OAc)7} n ] and the dimeric [C2mim]2[Ln2(OAc)8], based on the ion size and the ratio of IL used. A reaction with an IL : Ln‐salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy−Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal‐acetate coordination modes where η 2 μκ 2 is the most represented in both structure types., A straightforward pathway to synthesize anhydrous lanthanide acetate complexes from lanthanide chloride hydrates and the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium acetate ([C2mim][OAc]) is described. The combination of the lanthanide size and the amount of IL introduced allows the selective formation of two isostructural crystalline anhydrous compounds the dimeric, [C2mim]2[Ln2(OAc)8], and the polymeric, [C2mim] n [{Ln2(OAc)7} n ].

International audience; Colloidal bismuth therapeutics have been used for hundreds of years, yet remain mysterious. Here we report an X-ray pair distribution function (PDF) study of the solvolysis of bismuth disalicylate, a model for the metallodrug bismuth subsalicylate (Pepto-Bismol). This reveals catalysis by traces of water, followed by multistep cluster growth. The ratio of the two major species, {Bi9O7} and {Bi38O44}, depends on exposure to air, time, and the solvent. The solution-phase cluster structures are of significantly higher symmetry in comparison to solid-state analogues, with reduced off-center Bi3+ displacements. This explains why such “magic-size” clusters can be both stable enough to crystallize and sufficiently labile for further growth.

We report the first systematic experimental and theoretical study of the relationship between the linker functionalization and the thermodynamic stability of metal-organic frameworks (MOFs) using a model set of eight isostructural zeolitic imidazolate frameworks (ZIFs) based on 2-substituted imidazolate linkers. The frameworks exhibit a significant (30 kJ·mol-1) variation in the enthalpy of formation depending on the choice of substituent, which is accompanied by only a small change in molar volume. These energetics were readily reproduced by density functional theory (DFT) calculations. We show that these variations in the enthalpy of MOF formation are in linear correlation to the readily accessible properties of the linker substituent, such as the Hammett σ-constant or electrostatic surface potential. These results provide the first quantifiable relationship between the MOF thermodynamics and the linker structure, suggesting a route to design and tune MOF stability.