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The manner of bonding between constituent atoms or molecules invariably influences the properties of materials. Perhaps no material family is more emblematic of this than porous frameworks, wherein the namesake modes of connectivity give rise to discrete subclasses with unique collections of properties. However, established framework classes often display offsetting advantages and disadvantages for a given application. Thus, there exists no universally applicable material, and the discovery of alternative modes of framework connectivity is highly desirable. Here we show that chalcogen bonding, a subclass of σ-hole bonding, is a viable mode of connectivity in low-density porous frameworks. Crystallization studies with the triptycene tris(1,2,5-selenadiazole) molecular tecton reveal how chalcogen bonding can template high-energy lattice structures and how solvent conditions can be rationalized to obtain molecularly programmed porous chalcogen-bonded organic frameworks (ChOFs). These results provide the first evidence that σ-hole bonding can be used to advance the diversity of porous framework materials.

We report a new naphthalene bis(4,8-diamino-1,5-dicarboxyl)amide (NBA) building block for polymeric semiconductors. Computational modeling suggests that regio-connectivity at the 2,6- or 3,7-NBA positions strongly modulates polymer backbone torsion and, therefore, intramolecular π-conjugation and aggregation. Optical, electrochemical, and X-ray diffraction characterization of 3,7- and 2,6-dithienyl-substituted NBA molecules and corresponding isomeric NBA-bithiophene copolymers P1 and P2, respectively, reveals the key role of regio-connectivity. Charge transport measurements demonstrate that while the twisted 3,7-NDA-based P1 is a poor semiconductor, the planar 2,6-functionalized NBA polymers (P2–P4) exhibit ambipolarity, with μe and μh of up to 0.39 and 0.32 cm2/(V·s), respectively.

We report the synthesis and characterization of new alkyl-substituted 1,4-di(thiophen-2-yl)buta-1,3-diyne (R-DTB) donor building blocks, based on the −C≡C–C≡C– conjugative pathway, and their incorporation with thienyl-diketopyrrolopyrrole (R′-TDPP) acceptor units into π-conjugated PTDPP-DTB polymers (P1–P4). The solubility of the new polymers strongly depends on the DTB and DPP solubilizing (R and R′, respectively) substituents. Thus, solution processable and high molecular weight PDPP-DTB polymers are achieved for P3 (R = n-C12H25, R′ = 2-butyloctyl) and P4 (R = 2-ethylhexyl, R′ = 2-butyloctyl). Systematic studies of P3 and P4 physicochemical properties are carried using optical spectroscopy, cyclic voltammetry, and thermal analysis, revealing characteristic features of the dialkynyl motif. For the first time, optoelectronic devices (OFETs, OPVs) are fabricated with 1,3-butadiyne containing organic semiconductors. OFET hole mobilities and record OPV power conversion efficiencies for acetylenic organic ma...

The synthesis and characterization of a new family of thiophene bridged bis-naphthalimides (2NDI-XT) are presented here. These semiconductors have been designed to have an even or an odd number of thiophene rings, with the aim of studying molecules with varying and alternant molecular dipolar moments, which are expected to significantly impact molecular packing. Following a theoretical analysis, the stability of a series of π-dimers showing either parallel or antiparallel packing dispositions has been predicted. Our results point out to a molecular packing motif in which both the NDI and oligothiophene fragments are cofacial for all the semiconductors investigated, regardless of their estimated molecular dipole moments. These, in principle, unexpected results are in good agreement with the field-effect mobilities measured in a bottom-gate top-contact transistor architecture, which show no straightforward correlation between device performance and dipolar moment. Ambipolar field-effect mobilities are recorded for the most extended π-systems, 5,5′-bis(2-hexyldecylbenzo[lmn]thieno[3′,4′:4,5]imidazo[2,1-b][3,8]phenanthroline-1,3,6(2H)-trione-10-yl)-2,2′-bithiophene, 2NDI-4T and 5,5′′-bis(2-hexyldecylbenzo[lmn]thieno[3′,4′:4,5]imidazo[2,1-b][3,8]phenanthroline-1,3,6(2H)-trione-10-yl)-2,2′:5′,2′′-terthiophene, 2NDI-5T, with the latter showing quite balanced electron and hole mobilities of 1.8 × 10−3 cm2 V−1 s−1 and 8.4 × 10−3 cm2 V−1 s−1, respectively.

LiMn2O4 (LMO) spinels with diverse achievable morphologies are realized using solution processing techniques including sol-gel and cofuel-assisted combustion synthesis (CS). These LMOs are utilized as cathode materials in lithium ion batteries (LiBs), with LMO produced here by low-temperature, sorbitol-assisted combustion synthesis (SA-CS) yielding superior performance metrics. Morphological analysis by combined X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy demonstrates that these SA-CS LMO powders have optimum LiB grain (

We report the synthesis and properties of three novel acetylenic materials based on the new electron-rich building block, 2,2′-ethyne-1,2-diylbis[3-(alk-1-yn-1-yl)thiophene] (EBT). The synthesis of this new nonacene core is efficient and straightforward, and variation among n-hexyl, n-tetradecyl, and 2-ethylhexyl substituents substantially impacts the materials properties. Appending 2-ethylhexyl substituted diketopyrrolopyrrole (DPP) units to either terminus of the EBT core yields a series of low band gap molecules that are characterized in detail by a range of experimental microstructure and electronic structure probes and by density functional theory (DFT) computation. Detailed morphology/microstructure characterization of spin-cast films by X-ray diffraction and AFM reveals instructive microstructure and electronic/photovoltaic response relationships in both organic field-effect transistors and bulk-heterojunction organic photovoltaic cells. Thus, the former devices exhibit hole mobilities (μh) as larg...

The ionization potentials (IPs) and electron affinities (EAs) of widely used conjugated polymers are evaluated by cyclic voltammetry (CV) in conventional electrochemical and lithium-ion battery media, and also by ultraviolet photoelectron spectroscopy (UPS) in vacuo. By comparing the data obtained in the different systems, it is found that the IPs of the conjugated polymer films determined by conventional CV (IPC) can be correlated with UPS-measured HOMO energy levels (EH,UPS) by the relationship EH,UPS = (1.14 ± 0.23) × qIPC + (4.62 ± 0.10) eV, where q is the electron charge. It is also found that the EAs of the conjugated polymer films measured via CV in conventional (EAC) and Li(+) battery (EAB) media can be linearly correlated by the relationship EAB = (1.07 ± 0.13) × EAC + (2.84 ± 0.22) V. The slopes and intercepts of these equations can be correlated with the dielectric constants of the polymer film environments and the redox potentials of the reference electrodes, as modified by the surrounding electrolyte, respectively.