Bridging Atoms Research Articles

Charge Transport Across Dynamic Covalent Chemical Bridges.

Relationships between chemical structure and conductivity in ordered polymers (OPs) are difficult to probe using bulk samples. We propose that conductance measurements of appropriate molecular-scale models can reveal trends in electronic coupling(s) between repeat units that may help inform OP design. Here, we apply the scanning tunneling microscope-based break-junction (STM-BJ) method to study transport through single-molecules comprising OP-relevant imine, imidazole, diazaborole, and boronate ester dynamic covalent chemical bridges. Notably, solution-stable boron-based compounds dissociate in situ unless measured under a rigorously inert glovebox atmosphere. We find that junction conductance negatively correlates with the electronegativity difference between bridge atoms, and corroborative first-principles calculations further reveal a different nodal structure in the transmission eigenchannels of boronate ester junctions. This work reaffirms expectations that highly polarized bridge motifs represent poor choices for the construction of OPs with high through-bond conductivity and underscores the utility of glovebox STM-BJ instrumentation for studies of air-sensitive materials.

Effect of Bridging Atom and Hydroxyl Position on the Antioxidant Capacity of Six Phenolic Schiff Bases

A series of new phenolic Schiff bases N,N-bis(2,3-dihydroxybenzyl-idene)-4,4’-diphenylmethane (3-DPM), and N,N-bis(2,5-dihydroxybenzylidene)-4,4’-diphenylmethane (5-DPM), for sulfide bridge N,N-bis(2,3-dihydroxybenzyl-idene)-4,4’-diphenyl sulfide (3-DPS), N,N-bis(2,5-dihydroxybenzylidene)-4,4’-diphenyl sulfide (5-DPS), N,N-bis(2,3-dihydroxybenzyl-idene)-4,4’-diphenyl disulfide (3-DPSS), and N,N-bis(2,5-dihydroxybenzylidene)-4,4’-diphenyl disulfide (5-DPSS) were synthesized by condensation of substituted 4,4’-diamino-bis-(4-aminophenyl) methane/sulfide with various substituted aldehydes. The synthesized molecules were characterized by physical data, elemental, IR and 1H-NMR analyses. The antioxidant ability of compounds was determined through the use in vitro assays such as DPPH• scavenging, ABTS, total antioxidant capacity (TAC), hydroxyl radical OH• scavenging, and reducing power capability. The antioxidant activity of the compounds increased slightly after changing the atom bridge and hydroxyl group position. The results showed that the compound 5-DPSS exhibited superior scavenging strength against DPPH (EC50 = 7.10 ± 0.16 μg/mL), whereas 3-DPSS showed the highest activity (EC50 = 1.36 ± 0.08 μg/mL) when inspected by ABTS in relation to butylated hydroxyanisole (BHA) (EC50 = 7.54 ± 0.67). The higher OH• activity was marked by the compound 5-DPS (EC50 = 44.9 ± 3.3 μg/mL) related to BHT at (EC50 = 98.73 ± 0.3 μg/mL). The compounds 5-DPM demonstrated remarkable activity both reducing power (EC50 = 53.2 ± 0.3 μg/mL), and TAC assay (EC50 = 620.0 ± 2.4 μg/mL). These results prove that the modification in hydroxyl group position affect the antioxidant ability of Schiff bases.

Novel metal graphene framework (MGF) structures for hydrogen storage

Hierarchical novel metal graphene framework (MGF) structures designed, constructed and used for hydrogen storage by adsorption. Three different amounts of pillars used for connecting carboxylate functionalized graphene layers. The three-dimensional atomistic models optimized and then the aqua molecules removed which are coordinated to metal between graphene layers as bridge. Hydrogen storage abilities of aqua free models also investigated. The aqua existence made the structures more effective to store hydrogen according to simulation results. The highest storage capacity calculated for 181C.Aq named structure that includes aqua molecules inside could store 7.745 wt percentage hydrogen at 77 K and 100 bars pressure conditions. Hydrogen storage capacity decreases almost to half by removing aqua molecules for same structure. It is clear the coordinated aqua existence around the bridging atoms provides the spaces between graphene layers. In other word, the spaces between the graphene layers collapse by aqua removal so the hydrogen storage capacities decrease dramatically. Finally, spacing between graphene layers by bridges makes them very effective for hydrogen storage.

New electron transfer bridge construction between Ni3(HTTP)2 and graphene oxide layers for enhanced electrocatalytic oxidation of tetracycline hydrochloride

Electron transfer capability as crucial properties of anode is directly related to electrocatalytic performance. However, the contributions of electron transfer were always under estimated due to the ambiguous mechanism of electrocatalysis. In this paper, a new electron transfer bridge was constructed in Ni3(HTTP)2/GO to provide a new insight into electrocatalytic performance enhancement. The contributions of active sites candidates, including metal sites, ligands (metal bridging atoms), and electron transfer bridges were innovatively separated. As replacement experimental results (of metal sites and metal bridging atoms), both metal sites and metal bridging atoms contributed slightly as the active center directly for the electrocatalytic degradation of tetracycline hydrochloride (TCH). The great improvement was attributed to the generation of “GO-C-O-S-C-Ni3(HTTP)2” bridges, in which S atoms from ligands were critical anchoring sites for the connection of two 2D layers (Ni3(HTTP)2 and GO layer). The experimental and density functional theory results showed Ni3(HTTP)2 could donate electrons to GO layers, leading the electrostatic imbalance of charge density to facilitate electron withdrawal from pollutions (not only TCH, but also dyes and complex microbial flora). The results of this paper provide a new strategy for improving electrocatalytic efficiency by adjusting electron transfer for novel practical applications of Ni3(HTTP)2/GO composites.

Reversible First-Order Single Crystal to Single Crystal Thermal Phase Transition in [(CH3)3CNH3]4[V4O12

The well-known compound tetrakis(tert-butylammonium)-cyclo-tetrametavanadate (V), [(CH3)3CNH3]4[V4O12] (1h_RT), which crystallizes in the tetragonal I4/m space group, undergoes an irreversible solid state transformation upon heating, constituting one of the few examples in which the initial and the final stages are structurally characterized by sc-XRD. Now, we observed the ability of the same compound to undergo an additional single-crystal-to-single-crystal (SCSC) transformation upon thermal stimuli, but this time at low temperatures (153 K). Compound 1h_RT contains a discrete unprotonated [V4O12]4− tetrahedral anion in which V and O bridging atoms are coplanar. In both phases, these tetrameric anions are linked through tert-butylammonium cations in an extensive network of hydrogen bonds, but at low temperatures, this phase loses its characteristic O-V-O coplanarity, with the resulting rearrangement of the crystal packing and hydrogen-bond network which provide its reversibility at low temperatures. Again, the initial and final stages have been characterized structurally by sc-XRD.

Structural study of Li2S-GeS2 glasses: Ge[sbnd]S network and local environment of Li

The static structures of (Li2S)x(GeS2)100-x glasses (x = 0, 20, 30, 40 and 50) were investigated by using a combination of diffraction measurements and simulation techniques. The X-ray diffraction results show that the host GeS network is formed by linkages of GeS4 tetrahedra. The three-dimensional structure models of GeS network were generated by using the X-ray diffraction data and reverse Monte Carlo (RMC) simulation. The RMC models show that the number of edge-sharing GeS4 tetrahedra decreases as Li2S content but its ratio to the number of connections between GeS4 tetrahedra remains substantially constant irrespective of the composition. The Li ion sites in the GeS network structures were determined by molecular dynamics (MD) simulation with reference to the previously reported neutron diffraction data. The MD results show that each Li ion is located in a deformed octahedral site consisting of bridging and non-bridging sulphur atoms.

Chemical functionalization of low-buckled SiGe monolayer: Effects on the electronic and magnetic properties

Surface modification has been widely employed to modify fundamental properties of two-dimensional (2D) materials and create new multifunctional candidates for practical applications. In this work, the effects of chemical functionalization on silicon germanide (SiGe) monolayer have been investigated using first-principles calculations. Pristine monolayer exhibits good dynamical stability and a Dirac cone at K point in the band structure. The nearly semimetallic nature and absence of magnetic properties represent great challenge for SiGe monolayer applications. Our results show that these deficiencies can be overcome with oxygenation and hydrogenation processes. Oxygen (O) and hydrogen (H) atoms prefer to be adsorbed on-top of bridge and Si atom, respectively. The non magnetic nature is preserved under oxygenation, however a significant band gap up to 1.35 eV can be introduced depending on the O concentration. Meanwhile, the ferromagnetic semiconducting is induced by hydrogenation, where magnetic properties are produced mainly by Ge atoms, regardless the H coverage. In fact, efficient methods have been introduced to make SiGe monolayer promising 2D material for optoelectronic and spintronic applications through adsorbing O and H atoms.

Exploring the structure of pure germanophospate glasses with different concentrations probed by magic angle spinning NMR spectroscopy.

Phosphate-based glasses such as pure germanophosphate can be achieved at moderately low temperature by means of affordable chemical substances. Nowadays, they become more stimulating because they can be easily doped with alkali, transition metal ions, and rare earth oxides to afford the anticipated physical and/or chemical features for nanoscience applications. Herein, we report an experimental study dealing with the structure of pure germanophosphate glass samples of prepared with different concentrations ranging from 20 up to 70 mole%. 31 P magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy has been employed to characterize the co-formed glasses by two different glass-forming oxides. The components of the phosphate species ( ) in each sample were determined by analyzing the MAS NMR spectra. Interestingly, 31 P MAS NMR spectrum for each sample was found to be characteristic powder patterns of the middle units Q2 . Q2 unit found herein has one oxygen atom bonded towards one germanium atom (non-bridging) and the other two oxygens are bonding towards two phosphorus atoms (bridging) of phosphate group (PO4 ). The results show that Q2 split into two units, Q2 I and Q2 II, due to different shielding of the phosphorus nucleus provided by the next nearest neighbor atoms. The chemical shift is interpreted in terms of the structure of each building unit of the phosphate group. The results obtained herein shed light on the way how to explore the revealed structure of the prepared glasses for the development of supported catalysts. Indeed, owing to their high chemical/thermal stability, the co-formed germanophosphate glasses obtained may prove as useful substrates for potential nanocatalysts.

Atomic Bridging of Metal‐Nitrogen‐Carbon toward Efficient Integrated Electrocatalysis

AbstractThe rational design of robust electrocatalysts for efficient integrated devices is crucial to enhance energy conversion performance. The coordination of organic ligands with metal ions provides high flexibility to anchor metal atoms among carbon materials. Herein, the atomic anchoring of Zn and Ni atoms into N‐doped carbon networks with adjustable atomic structure is developed by the facile pyrolysis of metal‐organic framework nanoplates in the presence of dicyandiamide. Theoretical calculations reveal the descriptor‐based design principles to adjust the bridging structures of metal‐nitrogen‐carbon moieties with changing d‐band centers, thereby improving electrocatalytic performance. The resulting electrocatalyst displays good multiple electrocatalytic activities for carbon dioxide reduction, oxygen reduction, and evolution reactions, enabling the fabrication of integrated energy devices. Importantly, the CO2‐H2O overall splitting with the as‐prepared electrocatalysts has been driven by the commercial solar cell and the zinc‐air battery assembled with the same catalyst respectively, showing high CO faradaic efficiency up to 90%. Especially, the overall solar‐to‐CO conversion efficiency is up to 13% and the corresponding utilization efficiency of solar‐to‐electricity can reach 54.4%, demonstrating the large promising space to chase the limit that solar cells can possibly achieve. This work provides new opportunities to modulate the atomic bridging structure of metal‐nitrogen‐carbon for integrated electrolysis.

Catalytic mechanism of DcsB: Arginase framework used for hydrolyzing its inhibitor.

DcsB, an enzyme produced from the d-cycloserine biosynthetic gene cluster, displays moderate similarity to arginase in the sequence and three-dimensional structure. Arginase is a ubiquitous enzyme hydrolyzing l-arginine to generate l-ornithine and urea, whereas DcsB hydrolyzes Nω -hydroxy-l-arginine (l-NOHA), an arginase inhibitor, to generate l-ornithine and hydroxyurea. We determined the crystal structure of DcsB associated with l-ornithine and that with the tetrahedral derivative of 2(S)-amino-6-boronohexanoic acid, whose boron atom forms a covalent bond with an oxygen atom bridging two manganese ions at the active center. The substrate-binding pocket of DcsB is narrower than that of arginase, suggesting that DcsB is unsuitable for the binding of l-NOHA in an inhibitory manner. The transition state-like structure demonstrated that Asp210 and Glu241 have a role to trap a positively charged ion near the dimanganese cluster. Kinetic analysis using the mutated DcsB showed that the enzyme employs different catalytic mechanisms under the neutral and alkaline pH conditions. Glu241 in DcsB is likely involved in the recognition of the hydroxyguanidino group of l-NOHA, whereas Asp210, in cooperation with Glu241, seems to contribute to the reactivity toward the protonated l-NOHA, which is a preferable species under the neutral pH conditions. After entering of the protonated l-NOHA to the substrate-binding pocket of DcsB, a hydronium ion may be trapped at the positive ion-binding site. Then, the ion serves as a specific acid catalyst to facilitate the collapse of the tetrahedral intermediate of l-NOHA.

Paradimorphite, β-As4S3, a vintage new mineral from Solfatara di Pozzuoli and Vesuvius, Napoli, Italy

AbstractThe new mineral paradimorphite corresponds to the high temperature polymorph of As4S3, whose existence was supposed by Arcangelo Scacchi in 1850 in the fumaroles at the Solfatara di Pozzuoli, Campi Flegrei, near Napoli, Italy.Crystals of paradimorphite are orange yellow, transparent or semitransparent, with adamantine lustre. Habit is prismatic and observed forms are {110}, {101}, {111}, {100}, {010} and {001}. Tenacity is brittle, no distinct cleavage is observed and fracture is conchoidal. The mineral does not fluoresce in long- or shortwave ultraviolet light. No twinning is apparent. The streak is saffron yellow. Hardness (Mohs) = 1–2. The observed density is 3.510(3) g/cm3, calculated density is 3.500 g/cm3. The mineral is orthorhombic, space group Pnma, with a = 9.1577(7), b = 8.0332(6), c = 10.2005(8) Å, V = 750.41(10) Å3 and Z = 4. The eight strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 6.299(48)(011), 5.186(100)(111), 4.174(31)(201), 3.133(34)(022), 3.116(58)(212), 2.980(41)(122), 1.846 (27)(413) and 1.808(23)(134). The structure was refined to R = 0.0229 for 979 reflections with I >2σ(I). Crystals of paradimorphite contain As4S3 molecules, of idealised C3v symmetry, with the four arsenic atoms in a triangular pyramidal arrangement, with sulfur atom bridges on the three adjacent apical edges. Molecular dimensions and conformation are identical within standard uncertainties with those of the low-temperature polymorph dimorphite. No substantial differences, neither in the molecular packing nor in the molecular orientation, could be observed; minor differences being related to intermolecular distances only.

Computational study of ground-state properties of μ2 -bridged group 14 porphyrinic sandwich complexes.

The structural properties of μ2 -bridged porphyrinic double-decker complexes are investigated and the influence of various ligands, metals, substituents, and bridging atoms on the dominant structural motif is elucidated. A variety of quantum chemical methods including semiempirical (SQM) methods and density functional theory (DFT) is assessed for the calculation of ecliptic and staggered conformational energies. Local coupled cluster (DLPNO-CCSD(T1)) data are generated for reference. The r2 SCAN-3c composite scheme as well as the B2PLYP-D4/def2-QZVPP approach are identified as reliable methods. Energy decomposition analyses (EDA) and localized molecular orbital analyses (LMO) are used to investigate the bonding situation and the nature of the inter-ligand interaction energy underlining the crucial role of attractive London dispersion interactions. Targeted modification of the bridging atom, e.g., by replacing O2- by S2- is shown to drastically change the major structural features of the investigated complexes. Further, the influence of different substituents of varying size at the phthalocyanine ligand regarding the dominant conformation is described.

Synergistic effect of amide and fluorine of polymers assist stable inverted perovskite solar cells with fill factor > 83%

Exploring hole transporting materials (HTMs) with defect passivation function is an effective way to suppress the defect-induced non-radiative recombination (NRR) process in perovskite solar cells (PSCs). To date, most of these passivation materials are mainly devoted to passivate the uncoordinated Pb2+ of perovskite layer. However, ion migration processes of MA+ and I- in PSCs also cause a series of negative effects, which severely deteriorate the efficiency and device stability. Thus far, very few HTMs that can simultaneously passivate both the MA+/Pb2+ cations and I- anion defects in ABX3 structured perovskite. Herein, three dopant-free HTMs (BNs, BNs-F, and BNo-F) featuring multisite defect passivation function were developed for inverted PSCs. The carbonyl groups C = O and N–H in the amide linkers of BNs-F contributed to passivate the uncoordinated Pb2+ and the halide related defects, respectively. Simultaneously, the F atoms in bridges could interact with MA+ in perovskite via N-H‧‧‧F bond. Interestingly, an intermolecular hydrogen bond (O = C-N-H‧‧‧F) between amide linkers and F atoms was found in our work, which enabled BNs-F to achieve a high hole mobility of 2.42 × 10-4 cm2 V−1 s−1. Consequently, benefiting from the alleviated NRR behavior and enhanced charge transport ability, the optimized devices based on BNs-F realized a remarkable fill factor of 0.834, accompanying a champion efficiency up to 20.56% with superior long-term stability, exceeding those with BNs (19.03%), BNo-F (19.07%) and PTAA (19.56%). Our findings provide a guidance for design molecules with comprehensive passivation effect on MA+/Pb2+/I- defects to achieve efficient and stable PSCs.

Pyrene-Bridged Expanded Carbaporphyrin Nanobelts.

Two belt-like expanded carbaporphyrins (NB1 and NB2) were prepared via a one-pot procedure that involves a [6 + 3] condensation between a pyrene-bearing tetrapyrrole precursor (2) and pentafluorobenzaldehyde, followed by oxidation. Single crystal X-ray diffraction analyses revealed that NB1 and NB2 both contain six dipyrromethene moieties and three bridging pyrene units. In the structure of NB1, there are two vertically orientated pyrene units and one transverse orientated pyrene unit; however, in NB2 all three pyrene units are vertically orientated. The structural differences between NB1 and NB2 are reflected in their respective physical properties as revealed by proton NMR, UV-vis, and fluorescence spectroscopies. In contrast to all-carbon nanobelts, NB1 and NB2 contain multiple pyrrolic nitrogen donors that could serve as potential metal coordination sites. As a test of this possibility, NB2 was used to prepare an unprecedented Zn complex containing 7 Zn2+ metal centers connected by a network of bridging atoms, as confirmed by a single crystal X-ray diffraction analysis. To the best of our knowledge, this is the first example of a belt-like molecular system that can coordinate multiple metal ions both along the backbone and within its central cavity.

Evidence of humic acid-aluminium‑silicon complexes under controlled conditions

The chemistry of silicon (Si), the second most abundant element in soil after oxygen, is not yet fully understood in the soil-water-plant continuum. Although Si is widely accepted as an element that has little or no interaction with natural organic matter, some data seems to show the opposite. To identify a potential interaction between natural organic matter and Si, batch experiments were achieved at various pH and Si concentrations, involving also Al3+ as a common ion in soil and using humic acid (HA) as a typical model for natural organic matter. Several complementary techniques were used to characterize the possible complexes formed in the dissolved or solid phases: molecular fluorescence spectroscopy, 29Si solid-state NMR, Fourier transform infrared spectroscopy, quantification of Si, Al and organic carbon, and nanoparticle size distribution. These tools revealed that humic acid indeed interacts, but weakly, with Si alone. In the presence of Al, however, a ternary complex HA-Al-Si forms, likely with Al as the bridging atom. The presence of Si promotes the maintenance of both Al and dissolved organic matter (DOM) in solution, which is likely to modify the result or the kinetics of pedogenesis. Such complexes can also play a role in the control of Al toxicity towards plants and probably also exists with other metals, such as Fe or Mn, and other metalloids such as As.

Germanium‐Carbdiyne: A 3D Well‐Defined sp‐Hybridized Carbon‐Based Material with Superhigh Li Storage Property

Carbyne delivers various excellent properties for the existence of the larger number of sp‐hybridized carbon atoms. Here, a 3D well‐defined porous carbon material germanium‐carbdiyne (Ge‐CDY) which is comprised of only sp‐hybridized carbon atoms bridging by Ge atoms has been developed and investigated. The unique diamond‐like structure constructed by linear butadiyne bonds and sp3‐hybridized Ge atoms ensures the stability of Ge‐CDY. The large percentage of conjugated alkyne bonds composed of sp‐C guarantees the good conductivity and the low band gap, which were further confirmed experimentally and theoretically, endowing Ge‐CDY with the potential in electrochemical applications. The well‐defined 3D carbon skeleton of Ge‐CDY provides abundant uniform nanopores, which is suitable for metal ions storage and diffusion. Further half‐cell evaluation also demonstrated Ge‐CDY exhibited an excellent performance in lithium storage. All those indicating sp‐hybridized carbon‐based materials can exhibit great potential to possess excellent properties and be applied in the field of energy, electronic, and so on.

Synthesis and structural characterization of some 1:1 adducts of silver(I) salts with (hindered) PR3 bases (R = phenyl, o-tolyl, cyclohexyl)

Syntheses, spectroscopy and single crystal X-ray structural characterizations are recorded for a number of adducts AgX: PR3 (1:1)n obtained from the reaction of silver(I) salts with sterically hindered tertiary phosphine bases, extending previous studies. With tris(o-tolyl)phosphine, P(o-tolyl)3, binuclear adducts AgX: P(o-tolyl)3 (1:1)2 are defined, in arrays with eight-membered central rings [(o-to1yl)3PAg(μ-tfa)2AgP(o-tolyl)3] (1) (tfa = trifluoroacetate, O.CO.CF3) where two independent atoms of the anion bridge to the two silver atoms, and four-membered central rings where one atom bridges (Cl, NCO, acetate (= 'ac', O.CO.CH3)) (complexes 2–4); the perchlorate (5) is intermediate, one perchlorate bridging via one oxygen and the other by two. The nitrate is mononuclear, [(o-tolyl)3PAgO2NO], (6) with chelating nitrate. The bromide takes a tetranuclear 'cubane' form (7). With the cyanide, an interesting 2:1 AgCN: (o-tolyl)3P adduct (8) is defined as a two-dimensional polymer. The archetypical cubane series with triphenylphosphine is extended with a new bromide structure, MeCN solvated [(Ph3P)AgBr]4.0.22MeCN (9), to encompass also the cyanate [(Ph3P)Ag(NCO)]4 (10), isomorphous with the previously defined Cu/As/I chloroform solvate. The 'cubane' form is defined also for a further iodide polymorph AgI: Pcy3 (1:1)4 (11).

Structures and Electron Affinities of Aluminum Hydride Clusters AlnH (n = 3-13).

Low-energy structures and electron affinities (EAs) for aluminum hydride clusters AlnH (n = 3-13) have been calculated using ab initio and density functional calculations. Geometries were optimized at the PBE0/def-2-TZVPP level of theory, which has been shown to match the currently accepted lowest-energy structures for the all-aluminum clusters Aln and their anions. Neutral hydride clusters with n = 4, 7, and 9-12 are predicted to adopt terminal structures with the hydrogen atom bound to only one aluminum atom and with only minor alterations of the aluminum atom arrangement from that of the all-aluminum cluster. Clusters with n = 3 and 13 are predicted to adopt "face-centered" geometries, and the n = 6 cluster is predicted to prefer an isomer with the hydrogen atom bridging two aluminum atoms, also with little or no distortion to the aluminum atom arrangement from the all-aluminum cluster. Addition of a hydrogen atom to clusters with n = 5 and 8 is predicted to distort the aluminum atom arrangement significantly from that of the corresponding all-aluminum cluster. In the anionic clusters, terminal clusters are preferred for all cluster sizes except for n = 6 that prefers a face-centered arrangement. Minor distortions in the aluminum scaffolding for Al11 and Al12 were found, while all other anionic clusters adopt structures with little or no deviation in the aluminum atom arrangement from the corresponding all-aluminum cluster. Raw adiabatic electron affinities were computed using CCSD(T)/aug-cc-pVTZ single-point energies for the anionic and neutral hydride clusters at their respective DFT geometries. Isodesmic electron affinities for the hydride clusters were computed relative to their all-aluminum counterparts and show an even-odd alternation with cluster size. Derived EAs alternate in magnitude between even- and odd-numbered clusters, with the even-numbered clusters having relatively larger EAs.

High-performance heptacyclic ladder-type heteroarene-based electron acceptors enabled by bulky neighboring side-chains and end-group fluorination

A banana-shape heptacyclic heteroarene core without sp 3 -hybridized bridging atoms is designed and synthesized for constructing novel nonfullerene acceptors. Through introducing bulky neighboring side-chains and fluorinated terminals, molecular aggregation and crystallinity of the nonfullerene acceptors can be effectively modulated, thus leading to improved charge transport and device performance. • Non-fullerene acceptors with sp 3 -hybridized-carbon-free skeletons are developed. • Bulky neighboring side-chains leads to acceptors with suitable aggregation. • End-group fluorination leads to a 6-fold increase in the efficiency of acceptor. • An “A-to-D” type J -aggregation is observed for the acceptor. Although ladder-type heteroarene building blocks without sp 3 -hybridized bridging atoms have been widely used for the synthesis of polymer donors, they have rarely been applied for constructing non-fullerene acceptors (NFAs) mainly due to the lack of strategies to effectively modulate self-aggregation and crystallinity of the resulting acceptors. Herein, a novel sp 3 -hybridized-carbon-free ladder-type skeleton, benzo[2,1-b:3,4-b']bis(4H-dithieno[3,2-b:2′,3′-d]pyrrole) featuring with two sets of neighboring side-chains, is designed and successfully synthesized as a donor core for developing NFAs ( cis -MH and cis -MF). The single-crystal result shows that the cis -MF forms slip-stacked J -type aggregates and packs in an anti-parallel “face-to-face” manner due to the bulkiness effect of neighboring side-chains. This molecular stacking mode effectively prevents the formation of oversized aggregates in the corresponding active layer as evidenced by atomic force microscopy analyses. Introduction of the fluorinated terminals broadens the absorption range and increases the crystallinity of the acceptor, thus greatly promoting its carrier transport. As a result, the cis -MF-based device exhibits a 6-fold increase in power conversion efficiency compared to the cis -MH-based device. Overall, this work provides a new molecular design strategy as well as a novel sp 3 -hybridized-carbon-free ladder-type building block for developing efficient NFAs that can be used to further advance the PCEs of polymer solar cells.

Geometrical Structures and Dissociation Channels of CuP2n + (n = 2-11): Studied by Mass Spectrometry and Theoretical Calculations.

Transition metal phosphorus cluster cations CuP2n+ (2 ≤ n ≤ 11) were studied by laser ablation mass spectrometry and collision-induced dissociation (CID). The magic-numbered cluster ion of CuP8+ was identified experimentally, and cluster ions of CuP14+ and CuP18+ were also found to be generated with high abundance. CID results show that the dissociation channels of CuP2n+ (n = 4 and 6–10) are all characterized by the loss of the P4 unit. Theoretical calculations combining global minima searching with the basin-hopping method and density functional theory (DFT) optimizations were performed for these clusters. Among them, the magic-numbered cluster CuP8+ was characterized by a D2d symmetry, with the Cu atom bridging two P4 units. The most stable isomer of CuP14+ was found to be characterized by a C2v symmetry. Calculations also reflect that the dissociation channels of the loss of the P4 unit are more energetically favorable than those of the loss of the P2 unit for CuP2n+ (n = 4 and 6–10), which are in good consistent with the experimental results.