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Understanding excited-state reorganization energies, exciton diffusion lengths and non-radiative (NR) recombination, and the overall optoelectronic responses of nonfullerene small molecule acceptors (NF-SMAs) is important in order to rationally design new materials with controlled properties. While the effects of structural modifications on the optical gaps and electron affinities of NF-SMAs have been studied extensively, analyses of their absorption spectra that carefully characterize electronic and vibrational contributions that allow comparisons of reorganization energies and their implications for exciton diffusion lengths and NR recombination have yet to be reported. Here, we study the room temperature absorption spectra of three structural classes of NF-SMAs in dilute solutions through multiparameter Franck Condon (MFC) analyses and density functional theory (DFT) calculations. We show that the absorption spectra of these NF-SMAs can be categorized based on molecular structure-spectra correlation. The absorption spectra of curved, Y6-like structures can be described using an MFC model with two electronic transitions and two effective vibrational modes. The results of MFC/DFT analyses reveal that Y6 exhibits the smallest intra-molecular reorganization energy among the materials studied. Linear ITIC-like molecular structures reveal larger reorganization energies and reduced conformational uniformity compared to Y6. Meanwhile structures such as IDTBR and IEICO, which have an extra π-conjugated moiety between the donor and acceptor moieties, have large excited-state reorganization energies and low degrees of conformational uniformity. Since the intra-molecular reorganization energy is correlated with exciton diffusion length and nonradiative voltage losses (Δ

Accelerating the development of π-conjugated molecules for applications such as energy generation and storage, catalysis, sensing, pharmaceuticals, and (semi)conducting technologies requires rapid and accurate evaluation of the electronic, redox, or optical properties. While high-throughput computational screening has proven to be a tremendous aid in this regard, machine learning (ML) and other data-driven methods can further enable orders of magnitude reduction in time while at the same time providing dramatic increases in the chemical space that is explored. However, the lack of benchmark datasets containing the electronic, redox, and optical properties that characterize the diverse, known chemical space of organic π-conjugated molecules limits ML model development. Here, we present a curated dataset containing 25k molecules with density functional theory (DFT) and time-dependent DFT (TDDFT) evaluated properties that include frontier molecular orbitals, ionization energies, relaxation energies, and low-lying optical excitation energies. Using the dataset, we train a hierarchy of ML models, ranging from classical models such as ridge regression to sophisticated graph neural networks, with molecular SMILES representation as input. We observe that graph neural networks augmented with contextual information allow for significantly better predictions across a wide array of properties. Our best-performing models also provide an uncertainty quantification for the predictions. To democratize access to the data and trained models, an interactive web platform has been developed and deployed.

The shift of energy production towards renewable, yet at times inconsistent, resources like solar and wind have increased the need for better energy storage solutions. An emerging energy storage technology that is highly scalable and cost-effective is the redox-flow battery comprised of redox-active organic materials. Designing optimum materials for redox flow batteries involves balancing key properties such as the redox potential, stability, and solubility of the redox-active molecules. Here, we present the Data-enabled Discovery and Design to Transform Liquid-based Energy Storage (D3TaLES) database, a curated data collection of more than 43,000 redox-active organic molecules that are of potential interest as the redox-active species for redox flow batteries with the aim to offer readily accessible and uniform data for big data metanalyses. D3TaLES raw data and derived properties are organized into a molecule-centric schema, and the database ontology contributes to the establishment of community reporting standards for electrochemical data. Data are readily accessed and analyzed through an easy-to-use web interface. The data infrastructure is coupled with data upload and processing tools that extract, transform, and load relevant data from raw computation or experimental data files, all of which are available to the public via a D3TaLES API. These processing tools along with an embedded high-throughput computational workflow enable community contributions and versatile data sharing and analysis, not only in redox-flow battery research but also in any field that applies redox-active organic molecules.

The advance non-aqueous redox flow batteries require redox-active organic molecules (ROM) with large solubilities in all states of charge (NMR-spectrometer icon by DBCLS and screen and workstation icons by Simon Duerr licensed under creative commons).

An approach that combines atomistic molecular dynamics simulations and graph characterization is developed and deployed to follow the growth of organic crystals from the melt.

Molecular systems are analyzed via the construction of a molecular graph and quantifying the resiliency for charge transport through metrics for graph centrality, in the context of charge pathways between the source and drain electrodes.

Organic semiconductors offer tremendous potential across a wide range of (opto)electronic applications. However, the development of these materials is limited by trial-and-error design approaches, as well as computationally heavy modeling approaches to evaluate/screen candidates using a suite of materials descriptors. For the latter, for instance, density functional theory (DFT) methods are widely used to derive descriptors such as the oxidation and reduction potentials, molecular relaxation and reorganization energies, and intermolecular electronic couplings; these calculations are compute-intensive, often requiring hours to days to determine. Such bottlenecks slow the pace and limit the exploration of the vast chemical space that can comprise organic materials. Here, we introduce a machine learning (ML) model to predict intermolecular electronic couplings in organic, molecule-based crystalline materials that take a few seconds, as compared to hours by DFT. Further, we use the ML model in conjunction with mathematical formulations to rapidly screen the charge-carrier mobilities and associated anisotropies of over 60,000 molecular crystal structures. The ML models and pipeline are made fully available on the open-access OCELOT ML infrastructure.

We report the design, synthesis, and characterization of four N-annulated perylene diimide (NPDI) functionalized rhenium bipyridine [Re(bpy)] supramolecular dyads. The Re(bpy) scaffold was connected to the NPDI chromophore either directly [Re(py-C0-NPDI)] or via an ethyl [Re(bpy-C2-NPDI)], butyl [Re(bpy-C4-NPDI)], or hexyl [Re(bpy-C6-NPDI)] alkyl-chain spacer. Upon electrochemical reduction in the presence of CO2 and a proton source, Re(bpy-C2/4/6-NPDI) all exhibited significant current enhancement effects, while Re(py-C0-NPDI) did not. During controlled potential electrolysis (CPE) experiments at Eappl = -1.8 V vs Fc+/0, Re(bpy-C2/4/6-NPDI) all achieved comparable activity (TONco ∼ 25) and Faradaic efficiency (FEco ∼ 94%). Under identical CPE conditions, the standard catalyst Re(dmbpy) was inactive for electrocatalytic CO2 reduction; only at Eappl = -2.1 V vs Fc+/0 could Re(dmbpy) achieve the same catalytic performance, representing a 300 mV lowering in overpotential for Re(bpy-C2/4/6-NPDI). At higher overpotentials, Re(bpy-C4/6-NPDI) both outperformed Re(bpy-C2-NPDI), indicating the possibility of coinciding electrocatalytic CO2 reduction mechanisms that are dictated by tether-length and overpotential. Using UV-vis-nearIR spectroelectrochemistry (SEC), FTIR SEC, and chemical reduction experiments, it was shown that the NPDI-moiety served as an electron-reservoir for Re(bpy), thereby allowing catalytic activity at lower overpotentials. Density functional theory studies probing the optimized geometries and frontier molecular orbitals of various catalytic intermediates revealed that the geometric configuration of NPDI relative to the Re(bpy)-moiety plays a critical role in accessing electrons from the electron-reservoir. The improved performance of Re(bpy-C2/4/6-NPDI)dyads at lower overpotentials, relative to Re(dmbpy), highlights the utility of chromophore electron-reservoirs as a method for lowering the overpotential for CO2 conversion.

While it is known that the chain length strongly affects the properties of π-conjugated polymers, the effects of chain length on the molecular structure, chain conformation, and oxidation state pro...

As buzzwords like "big data," "machine learning," and "high-throughput" expand through chemistry, chemists need to consider more than ever their data storage, data management, and data accessibility, whether in their own laboratories or with the broader community. While it is commonplace for chemists to use spreadsheets for data storage and analysis, a move towards database architectures ensures that the data can be more readily findable, accessible, interoperable, and reusable (FAIR). However, making this move has several challenges for those with limited-to-no knowledge of computer programming and databases. This Perspective presents basics of data management using databases with a focus on chemical data. We overview database fundamentals by exploring benefits of database use, introducing terminology, and establishing database design principles. We then detail the extract, transform, and load process for database construction, which includes an overview of data parsing and database architectures, spanning Standard Query Language (SQL) and No-SQL structures. We close by cataloging overarching challenges in database design. This Perspective is accompanied by an interactive demonstration available at https://github.com/D3TaLES/databases_demo. We do all of this within the context of chemical data with the aim of equipping chemists with the knowledge and skills to store, manage, and share their data while abiding by FAIR principles.

The electronic and optical responses of an organic semiconductor (OSC) are dictated by the chemistries of the molecular or polymer building blocks and how these chromophores pack in the solid state. Understanding the physicochemical nature of these responses is not only critical for determining the OSC performance for a particular application, but the UV/visible optical response may also be of potential use to determine aspects of the molecular-scale solid-state packing for crystal polymorphs or thin-film morphologies that are difficult to determine otherwise. To probe these relationships, we report the quantum-chemical investigation of a series of trialkyltetrelethynyl acenes (tetrel = silicon or germanium) that adopt the brickwork, slip-stack, or herringbone (HB) packing configurations; the π-conjugated backbones considered here are pentacene and anthradithiophene. For comparison, HB-packed (unsubstituted) pentacene is also included. Density functional theory and G0W0 (single-shot Green’s function G and/or screened Coulomb function W) electronic band structures, G0W0-Bethe–Salpeter equation-derived optical spectra, polarized ϵ2 spectra, and distributions of both singlet and triplet exciton wave functions are reported. Configurational disorder is also considered. Furthermore, we evaluate the probability of singlet fission in these materials through energy conservation relationships.

First-principles thermodynamics enables the description of the surface chemistry of inorganic materials as a function of temperature and partial pressures of atmospheric gases, providing a framework to connect atomistic simulations with macroscopic materials properties. Here we re-examine the surface chemistry of LiFePO4 (LFP), a widely studied material for use as the cathode in Li-ion batteries. Our results reveal that at room temperature and under standard pressures the LFP (010) surface is covered with water. At elevated temperatures and reduced H2 partial pressure, one water molecule loses a hydrogen atom and the preferred binding moieties are OH and H2O; while further reducing the H2O partial pressure results in the desorption of water leaving only the OH behind. This work also shines new light on the configuration, and resulting electronic properties, of the LFP (010) surface when molecular oxygen (O2) is adsorbed. The molecular adsorbates are also shown to have an impact on the LFP surface potentials and magnetic properties. These simulations provide an enhanced picture of the LFP surface chemistry and the potential impact of these adsorbates on understanding the characteristics of LFP in different materials applications.

Summary 1,3-Dimethyl-2-(4-(dimethylamino)phenyl)-2,4-dihydro-1H-benzoimidazole, N-DMBI-H, is widely used as an air-stable n-dopant for organic semiconductors. Here, its reactivity is investigated with a variety of imide- and amide-containing semiconductor molecules that have reduction potentials in the range −0.54 to −1.10 V versus ferrocene. Reaction rates correlate poorly with these potentials. The more reactive of the imides form the corresponding radical anions cleanly, but kinetic isotope studies using N-DMBI-D indicate that the reaction proceeds via an initial hydride- or hydrogen-transfer step. For an amide- and ester-rigidified bis(styryl)benzene derivative the hydride-reduced product is stable under an inert atmosphere and can be observed directly; the radical anion can only be obtained in sub-stoichiometric yield and under certain reaction conditions. On the other hand, (N-DMBI)2 rapidly reduces all the imides and amides examined to the corresponding radical anions. The implications of these findings for dopant selection and use are discussed.

Rapid increase in the power conversion efficiency of organic solar cells (OSCs) has been achieved with the development of non-fullerene small-molecule acceptors (NF-SMAs). Although the morphological stability of these NF-SMA devices critically affects their intrinsic lifetime, their fundamental intermolecular interactions and how they govern property–function relations and morphological stability of OSCs remain elusive. Here, we discover that the diffusion of an NF-SMA into the donor polymer exhibits Arrhenius behaviour and that the activation energy Ea scales linearly with the enthalpic interaction parameters χH between the polymer and the NF-SMA. Consequently, the thermodynamically most unstable, hypo-miscible systems (high χ) are the most kinetically stabilized. We relate the differences in Ea to measured and selectively simulated molecular self-interaction properties of the constituent materials and develop quantitative property–function relations that link thermal and mechanical characteristics of the NF-SMA and polymer to predict relative diffusion properties and thus morphological stability. Studies on the morphology stability of polymer donor–small-molecule acceptor blends relevant to solar cell stability reveal relationships between their intermolecular interactions and the thermodynamic, kinetic, thermal and mechanical properties.

[RuCp*(1,3,5-R3C6H3)]2 {Cp* = η5-pentamethylcyclopentadienyl, R = Me, Et} have previously been found to be moderately air stable, yet highly reducing, with estimated D+/0.5D2 (where D2 and D+ represent the dimer and the corresponding monomeric cation, respectively) redox potentials of ca. −2.0 V vs. FeCp2+/0. These properties have led to their use as n-dopants for organic semiconductors. Use of arenes substituted with π-electron donors is anticipated to lead to even more strongly reducing dimers. [RuCp*(1-(Me2N)-3,5-Me2C6H3)]+PF6− and [RuCp*(1,4-(Me2N)2C6H4)]+PF6− have been synthesized and electrochemically and crystallographically characterized; both exhibit D+/D potentials slightly more cathodic than [RuCp*(1,3,5-R3C6H3)]+. Reduction of [RuCp*(1,4-(Me2N)2C6H4)]+PF6− using silica-supported sodium–potassium alloy leads to a mixture of isomers of [RuCp*(1,4-(Me2N)2C6H4)]2, two of which have been crystallographically characterized. One of these isomers has a similar molecular structure to [RuCp*(1,3,5-Et3C6H3)]2; the central C–C bond is exo,exo, i.e., on the opposite face of both six-membered rings from the metals. A D+/0.5D2 potential of −2.4 V is estimated for this exo,exo dimer, more reducing than that of [RuCp*(1,3,5-R3C6H3)]2 (−2.0 V). This isomer reacts much more rapidly with both air and electron acceptors than [RuCp*(1,3,5-R3C6H3)]2 due to a much more cathodic D2˙+/D2 potential. The other isomer to be crystallographically characterized, along with a third isomer, are both dimerized in an exo,endo fashion, representing the first examples of such dimers. Density functional theory calculations and reactivity studies indicate that the central bonds of these two isomers are weaker than those of the exo,exo isomer, or of [RuCp*(1,3,5-R3C6H3)]2, leading to estimated D+/0.5D2 potentials of −2.5 and −2.6 V vs. FeCp2+/0. At the same time the D2˙+/D2 potentials for the exo,endo dimers are anodically shifted relative to those of [RuCp*(1,3,5-R3C6H3)]2, resulting in much greater air stability than for the exo,exo isomer.

A carbon side-chain analogue to the high-performance organic semiconductor triethylsilylethynyl difluoroanthradithiophene has been synthesised and characterized. Atomic substitution of carbon for silicon results in subtle changes to opto-electronic properties, which are rationalised by density functional theory and balance of electron donating and withdrawing effects. Larger differences are observed in photostability and solid-state packing of the new material in comparison to known silicon and germanium derivatives. Comparison of the group 14 elements teaches us about the newly synthesised system, but also how the silylethynyl substituents used for the last two decades contribute to successful employment of functionalised polycyclic aromatic hydrocarbons as organic semiconductors.

Derived from the lateral fusion of benzene rings, acenes are a class of π-conjugated molecules containing a single aromatic sextet, where system size is inversely correlated with chemical stability. In the pursuit of creating graphene nanoribbons/nanowires, several extended-ring structures have been synthesized through linear combinations of azaacenes and pyrene. Importantly, these extended systems demonstrate enhanced chemical stability and allow for the construction of macromolecular-sized structures. Here, we present a combined quantum-chemical and experimental study to reveal the cost of these improved characteristics in fully carbon-based systems. The results clearly show that pyrene moieties inserted among acene units do not result in long acene-like structures, rather the pyrene-inserted acene is, electronically, a series of (nearly) isolated acenes. The origin of pyrene's electronic blocking effect and implications on oxidized and photoexcited states of these extended-ring systems are detailed. The results of this investigation definitively show that coupling pyrene in an orthogonal orientation (through the 4, 5/9, 10 positions or e/l faces) to acenes should be eschewed if nanographene-/nanowire-like structures are desired.

Despite recent literature reporting the remarkable electrochemical CO2 reduction reaction (CO2RR) performance of nitrogen-doped graphitic carbon materials (sp2-carbon) and nitrogen-doped diamond materials (sp3-carbon), no systematic studies have been conducted on the catalytic activities of hybrid carbon nanomaterials between diamond and graphitic extremes. In this study, nitrogen-doped ultra-nanocrystalline diamond thin films were prepared by a microwave-assisted chemical vapor deposition technique. The ratio of sp2-carbon phase to sp3-carbon phase was controlled by varying growth conditions. Our results confirm that nitrogen-doped sp2-carbon (graphitic) rich electrodes have better selectivity for the CO2RR products over the nitrogen-doped sp3-carbon rich electrodes, indicating that the host structure of nitrogen dopants is crucial for the catalytic activity. Nitrogen-doped sp2-carbon electrodes present Faradaic efficiency for CO production up to 82% with excellent activity and selectivity. The vital role of the host structure and the potential catalytic sites were detailed by density functional theory (DFT) calculations.

Fullerene fragments, referred to as buckybowls, are garnering interest due to their distinctive molecular shapes and optoelectronic properties. Here, we report the synthesis and characterization of a novel C70 subunit, diindeno[4,3,2,1-fghi:4',3',2',1'-opqr]perylene, that is substituted with either triethylsilyl(TES)-ethynyl or 2,4,6-triisopropylphenyl groups at the meta-positions. The resulting compounds (1 and 2) display a bowl-to-bowl inversion at room temperature. Notably, the substituent groups on the meta-positions alter both the geometric and the electronic properties as well as the crystal packing of the buckybowls. In contrast to the 2,4,6-triisopropylphenyl groups in 2, the TES-ethynyl groups in 1 lead to enhanced bond length alternation, resulting in weaker aromaticity of the six-membered rings of the buckybowl skeleton. 1 forms one-dimensional (1D) concave-in-convex stacking columns, and when 1 is blended with C70, the buckybowls encapsulate C70 and result in two-dimensional cocrystals. Organic field-effect transistor (OFET) measurements demonstrate that 1 displays a hole mobility of 0.31 cm2 V-1 s-1, and the 1-C70 cocrystal exhibits ambipolar transport characteristics with electron and hole mobilities approaching 0.40 and 0.07 cm2 V-1 s-1, respectively. This work demonstrates the potential of buckybowls for the development of organic semiconductors.

The alcohol and water-based processing of a perylene diimide (PDI) organic semiconductor into large area and solvent resistant films is reported. The compound, PDIN-H, is an N-annulated PDI dye with a pyrrolic NH functional group that can be deprotonated to render the material soluble in polar solvents. Addition of NaOH to mixtures of PDIN-H in 1-propanol results in a progressive color change from orange/red to purple with increasing equivalents of base. Use of 1 molar equivalent of NaOH was found to fully dissolve the PDIN-H in alcohol solvents up to a concentration of 10 mg mL−1. Primary alcohols 1-propanol to 1-hexanol as well as 2-propanol were used. All solutions were readily spin-coated or slot-die coated into uniform thin films. Solutions in 1-propanol could be coated with concentrations up to 50 mg mL−1. All films were red in color and characterized by optical absorption spectroscopy confirming the existence of the parent PDIN-H species in the film. Single crystal X-ray diffraction was used to determine the molecular packing of PDIN-H. Films showed no signs of dewetting, swelling, or dissolution upon exposure to 2-propanol, water, or o-xylene via coating or dipping indicating they were solvent resistant. To exploit the semiconducting properties of these PDIN-H films, organic photovoltaic devices were fabricated using the films as electron transport layers in inverted type P3HT:PC61BM bulk heterojunction devices. Moreover, the PDIN-H films changed from red to purple upon exposure to butylamine vapors which prompted the investigation of hydroxide free processing. Indeed, films of PDIN-H were easily formed by processing with 1-propanol/butylamine or water/butylamine solutions.

The advent of data analytics techniques and materials informatics provides opportunities to accelerate the discovery and development of organic semiconductors for electronic devices. However, the development of engineering solutions is limited by the ability to control thin-film morphology in an immense parameter space. The combination of high-throughput experimentation (HTE) laboratory techniques and data analytics offers tremendous avenues to traverse the expansive domains of tunable variables offered by organic semiconductor thin films. This Perspective outlines the steps required to incorporate a comprehensive informatics methodology into the experimental development of polymer-based organic semiconductor technologies. The translation of solution processing and property metrics to thin-film behavior is crucial to inform efficient HTE for data collection and application of data-centric tools to construct new process-structure-property relationships. We argue that detailed investigation of the solution state prior to deposition in conjunction with thin-film characterization will yield a deeper understanding of the physicochemical mechanisms influencing performance in π-conjugated polymer electronics, with data-driven approaches offering predictive capabilities previously unattainable via traditional experimental means.

We report the design, synthesis, and characterization of four N-annulated perylene diimide (NPDI) functionalized rhenium bipyridine [Re(bpy)] supramolecular dyads. The Re(bpy) scaffold was connected to the NPDI chromophore either directly [

[RuCp*(1,3,5-R

Silyl ethynyl groups have become commonplace in functionalizing organic semiconductors, where they improve solubility and stability. The identity of the side chain also dictates the molecular organization in the solid state, and thus heavily influence bulk material properties such as charge mobility. Germanium-containing side chains show the same propensity to form favorable solid state packing motifs, but carbon analogs remain mostly unexplored. Here we present a general synthesis of carbon alkynes, changes in molecular properties of acenes functionalised with these alkynes, and a rich variety in crystal packing motifs that have rarely been observed with silicon or germanium side chains.

The design of molecules and polymers for solution-deposited organic semiconducting materials generally considers the chemical modulation of (i) the π-conjugated backbone to modify the electronic and optical characteristics and (ii) the alkyl side chains to govern solubility. As the solid-state material forms, physical interactions among these constituents play an important, yet not well understood, role in directing the molecular-scale packing arrangements that in part determine the final material properties. In this presentation we will discuss how the dynamics of these moieties under different conditions, including the potential for conformational disorder among various points of torsion within the π-conjugated backbone, can impact aggregate formation and resulting solid-state morphology. The chemical insight developed through these investigations is beginning to refine and offer novel understanding essential to the development of next generation organic semiconducting active layers.

Chemists have the capability to tune the electronic, redox, and optical properties of π-conjugated molecules and polymers, which in turn are used as the building blocks to develop organic semiconductors. In these materials, the nature of the molecular-scale solid-state packing arrangement dictates performance, rendering knowledge as to how materials processing impacts these arrangements critical. Currently, there exist few hard-and-fast rules that combine molecular design and process conditions in the discovery of new organic semiconductors, as the understanding that links these domains is quite limited. Here, we will discuss the development of data-enabled tools, including an open-access database dedicated to crystalline organic semiconductors, that aim to seek out physicochemical understanding across the multiple physical and chemical scales that dictate performance and offer machine-based discovery and design of new generations of organic semiconductors.

Materials design and discovery are often hampered by the slow pace and materials and human costs associated with Edisonian trial-and-error screening approaches. Recent advances in computational power, theoretical methods, and data science techniques, however, are being manifest in a convergence of these tools to enable in silico materials discovery. Here, we present the development and deployment of computational materials data and data analytic approaches for crystalline organic semiconductors. The OCELOT (Organic Crystals in Electronic and Light-Oriented Technologies) infrastructure, consisting of a Python-based OCELOT application programming interface and OCELOT database, is designed to enable rapid materials exploration. The database contains a descriptor-based schema for high-throughput calculations that have been implemented on more than 56 000 experimental crystal structures derived from 47 000 distinct molecular structures. OCELOT is open-access and accessible via a web-user interface at https://oscar.as.uky.edu.

Controlling hierarchical structural development in organic semiconductors, and across synthetic materials more broadly, is critical to the performance of the material in device applications. Such r...

Alkyl chains of varied length and steric bulk are generally appended to π-conjugated chromophores to increase solubility. These alkyl chains also regulate many aspects of the solid-state packing an...

Anthropogenic greenhouse gas emissions, such as CO2 from fossil fuel combustion, are a global environmental, health, and economic concern. Aqueous amine-based CO2 capture processes offer a technologically mature and relevant approach to CO2 sequestration, although cost reduction strategies are still necessary for widespread deployment. Inspired by the metalloenzyme carbonic anhydrase (CA), we report the design, synthesis, and activity testing of zinc(II) complexes [ZnII(PSAAMP)Cl2] (1) and [ZnII(PSAMEA)Cl2] (2) as CO2 hydration catalysts in aqueous amine solutions. The novel multifunctional ligand environment includes features in the primary and secondary coordination spheres that result in enhanced CO2 mass transfer in industrially relevant carbon capture solvents and stability towards harsh industrial process conditions. Complexes that lack these key features do not show enhanced CO2 absorption. Density functional theory (DFT) calculations that assess the catalytic pathway demonstrate how 1 and 2 catalyze CO2 hydration analogous to CA. These catalysts increase mass transfer by 20–55% in lab scale experiments, offering the potential to reduce the cost of amine-based CO2 capture processes without significantly altering industrial-scale system design, making rapid deployment of this critical bridge technology a viable strategy to reduce global greenhouse gas emissions.

Charge-carrier transport in thin-film organic semiconductors is strongly related to the molecular structure and the solid-state packing, which in turn are dependent on materials processing and devi...

Functionalization of organic semiconductors through the attachment of bulky side groups to the conjugated core has imparted solution processability to this class of otherwise insoluble materials. A consequence of this functionalization is that the bulky side groups impact the solid-state packing of these materials. To examine the importance of side-group electronic character on accessing the structural phase space of functionalized materials, germanium was substituted for silicon in triisopropylsilylethynylpentacene (TIPS-Pn) to produce triisopropylgermanylethynylpentacene (TIPGe-Pn), with the TIPGe side group comparable in size to TIPS, but higher in electron density. We find TIPGe-Pn single crystals exhibit slip-stack, herringbone, and brickwork packing motifs depending on growth conditions, a stark contrast to TIPS-Pn, which accesses only the brickwork packing motif in both single crystals and thin films. Polycrystalline thin films of TIPGe-Pn exhibit two new, unidentified polymorphs from spin-coating ...

Both organic hydride donors, DH, and the dimers formed by some organic radicals and by some 19-electron organometallic sandwich compounds, D2, have recently been examined extensively as n-dopants for organic semiconductors. This properties of two classes of organometallic DH derivatives – organic DH derivatives with metallocenyl substituents and species obtained by hydride reduction of 18-electron D+ sandwich cations – are discussed and compared to those of the corresponding D2 molecules. 1,3-Dimethyl-2-metallocenyl-2,3-dihydro-1H-benzo[d]imidazoles, Mc-DMBI-H (Mc = ferrocenyl [Fc], ruthenocenyl [Rc]), and 1,3-dimethyl-2-phenyl-1H-benzo[d]imidazolium tetrakis(3,5-bis(trifluoromethyl))borates, Mc-DMBI+BAr'4– (Mc = Fc, Rc), have recently been reported as intermediates in the synthesis of the dimers (Mc-DMBI)2; here their crystal structures are reported and compared to those of related molecules. The solution reactivity of the Mc-DMBI-H derivatives with a fullerene acceptor is similar to that of purely organic aryl-DMBI-H species. Previously reported (exo-H-η4-pentamethylcyclopentadiene)(η5-cyclopentadienyl)metal complexes, M(exo-H-Cp*H)Cp (M = Rh, Ir) and the new (η5-pentamethylcyclopentadienyl)(η5-1,3,5-trimethylcyclohexa-1,3-dien-5-yl)ruthenium, RuCp*(mesH), have also been examined as potential reductants for organic semiconductors; RuCp*(mesH) is particularly reactive, affording the radical anions of perylene diimide and 6,13-bis(tri(isopropyl)silylethynyl)pentacene. The electrochemistry of DH, D+, and D2 species is compared for the five compounds. Density-functional theory calculations are used to gain insight into the trends in electrochemistry and reactivity.