Herringbone Motifs Research Articles

Tannic acid- and cation-mediated interfacial self-assembly and epitaxial growth of fullerene (nC60) and kaolinite binary graphitic aggregates

In this study, we investigated the tannic acid (TA)-, Ca2+-, and mica-enabled interfacial assembly of nC60 fullerene (FWS) and Na-saturated kaolinite (Na-Kl) with in and ex situ atomic force microscopy (AFM). The epitaxial growth of herringbone motif, two dimensional (2D) chiral clusters and 3D mounds were detected. π-π electron donor-acceptor (EDA) interactions drove the transformation of the FWS, and the symmetry of the muscovite substrate directed the epitaxial ordering of self-assembled herringbone motifs. A ternary mixture of Na-Kl/FWS/TA in the presence of Ca2+ produced double-stranded (ds) helices and 2D platelets of chiral clusters with a nano-porous monolayer on K+-treated muscovite surfaces. The weak hydration of exchangeable K+ and stronger electric fields possibly contributed to the 1D and 2D propagation of aggregates. However, the local increment in carbon content due to the nucleation of functionalized FWS on mica diminished the K+-induced electric field effect and facilitated the 3D growth of helical mounds. The diffusion limited mass-transfer of particulates across the Ehrlich-Schwoebel barrier (ESB) and screw dislocation assisted motion of particulates specifically at higher steps aided mound growth. Thus, the structural incorporation of FWS can substantially impede its interfacial transport and produce hierarchical hybrid mineral-enriched graphitic aggregates.

Impact of Atomistic Substitution on Thin-Film Structure and Charge Transport in a Germanyl-ethynyl Functionalized Pentacene

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 ...

Stacking Principles on π- and Lamellar Stacking for Organic Semiconductors Evaluated by Energy Decomposition Analysis.

Two stacking manners, that is, π- and lamellar stacking, are generally found for organic semiconductors, in which the π-stacking occurs between conjugated groups and the lamellar stacking refers to the separation of the conjugated and aliphatic moieties. The stacking principles are yet not well-defined. In this work, extended transition state–natural orbitals for chemical valence (ETS–NOCV), an energy decomposition analysis, is utilized to examine the π- and lamellar stacking for a series of naphthalenetetracarboxylic diimide (R-NDI) crystals. The crucial role of dispersion is validated. The perception that π-stacking is merely determined by the conjugated moiety is challenged. The stacking principles are associated with the closest packing model. Nanoscopic phase separation of conjugated and aliphatic moieties and the formation of lamellar and herringbone motifs in the R-NDIs can thus be clarified. Moreover, the interactions between NDI and the alkyl chain are investigated, revealing that the interactions can be significant, being contradictory to the conventional point of view. Along with R-NDIs, additional organic crystals consisting of various conjugated functionalities and substituents are also investigated by ETS–NOCV. The sampling scope is up to 108 conjugated molecules. The dominant role of dispersion force irrespective of the variation in the conjugated moieties and substituents is further confirmed. It is envisaged that the established principles are applicable to other organic semiconductors. The perspective toward the π- and lamellar stacking might be modified, paving the way for ultimate morphological control.

N-Oxide-N-oxide interactions and Cl...Cl halogen bonds in pentachloropyridine N-oxide: the many-body approach to interactions in the crystal state.

Pentachloropyridine N-oxide, C5Cl5NO, crystallizes in the monoclinic space group P21/c. In the crystal structure, molecules are linked by C-Cl...Cl halogen bonds into infinite ribbons extending along the crystallographic [100] direction. These molecular aggregates are further stabilized by very short intermolecular N-oxide-N-oxide interactions into herringbone motifs. Computations based on quantum chemistry methods allowed for a more detailed description of the N-oxide-N-oxide interactions and Cl...Cl halogen bonds. For this purpose, Hirshfeld surface analysis and the many-body approach to interaction energy were applied.

Strain induced polymorphism and band structure modulation in low-temperature 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene single crystal

Organic semiconductors are inherently soft, making it possible to increase their mobilities by strains. Such a unique feature can be exploited directly in flexible electronics for improved device performance. The 2,7-dioctyl[1]benzothieno[3,2-b][1]-benzothiophene derivative, C8-BTBT is one of the best small-molecule hole transport materials. Here, we demonstrated its band structure modulation under strains by combining the non-equilibrium molecular dynamics simulations and first-principles calculations. We found that the C8-BTBT lattice undergoes a transition from monoclinic to triclinic crystal system at the temperature below 160 K. Both shear and uniaxial strains were applied to the low-temperature triclinic phase of C8-BTBT, and polymorphism was identified in the shear process. The band width enhancement is up to 8% under 2% of compressive strain along the x direction, and 14% under 4% of tensile strain along the y direction. The band structure modulation of C8-BTBT can be well related to its herringbone packing motifs, where the edge to face and edge to edge pairs constitute two-dimensional charge transport pathways and their electronic overlaps determine the band widths along the two directions respectively. These findings pave the way for utilizing strains towards improved performance of organic semiconductors on flexible substrates, for example, by bending the substrates.

Divergent layer topologies in divalent metal aliphatic dicarboxylate coordination polymers containing 3-pyridylmethylnicotinamide

Hydrothermal reaction of the requisite metal salt, an aliphatic dicarboxylic acid, and the hydrogen-bonding capable dipyridylamide ligand 3-pyridylmethylnicotinamide (3-pmna) resulted in four coordination polymers whose connectedness and layer topology depend on the metal coordination environment and dicarboxylate binding mode. These new crystalline phases were characterized by single crystal X-ray diffraction. [Cu(ox)(3-pmna)]n (1, ox = oxalate) manifests stacked 3-connected (6,3) herringbone layer motifs. {[Cd(mal)(3-pmna)(H2O)]·3H2O}n (2, mal = malonate) shows a 4-connected (4,4) grid topology with entrained water molecule trimeric chains in the interlamellar regions. {[Cd2(suc)2(3-pmna)(H2O)2]·3H2O}n (3, suc = succinate) possesses {Cd2O2} dimer-based [Cd(suc)]n layers pillared by 3-pmna ligands into a 5-connected sandwich motif with 4862 topology. {[Cd(glu)(3-pmna)(H2O)]·3H2O}n (4, glu = glutarate) manifests a rippled (4,4) grid topology. Luminescent behavior in the cadmium complexes is ascribed to intra-ligand molecular orbital transitions. Thermal decomposition behavior is also discussed herein.

Cadmium carboxycinnamate coordination polymers with dimensionality differences depending on dipyridyl ligand

Hydrothermal reaction of cadmium nitrate, carboxycinnamic acid (H2cca), and a tethering hydrogen-bonding capable dipyridyl ligand afforded three new crystalline coordination polymers, which were characterized by single-crystal X-ray diffraction. {[Cd(cca)(dpa)2]·2H2O}n (1, dpa=4,4′-dipyridylamine) shows a (4,4) coordination polymer layer, but with pendant dpa ligands curling in through the grid apertures. {[Cd(cca)(4-bpmp)(H2O)]·2H2O}n (2, 4-bpmp=bis(4-pyridylmethyl)piperazine) also has a 2-D coordination polymer layer structure, but with closely interdigitated (6,3) herringbone motifs. [Cd(cca)(4-bpfp)]n (3, 4-bpfp=bis(4-pyridylformyl)piperazine) manifests a {Cd2(OCO)2} dimer-based 6-connected pcu 3-D network. All three materials undergo modest to strong blue-violet fluorescence under ultraviolet radiation. Thermal decomposition behavior is also probed.

Electronic Structures and Charge Transport of Stacked Annelated β-Trithiophenes

Density functional theory (DFT) calculations were performed using a MPWB1K functional to interpret the charge transport (CT) properties of stacked annelated β-trithiophene molecules. The goal was to help understand how the chemical composition, face-to-face stacking, intra- and intermolecular correlations, and the applied electric field affect the CT properties of this organic semiconductor compared with those of the edge-to-face "herringbone" motif. The variations in the frontier molecular orbitals, energy gap, nonadiabatic electron attachment energies (EAE), and vertical detachment energies (VDE) were investigated under an external electric field as a function of the number of stacked layers (n). Two possible CT pathways, monomer-to-monomer (MM) and dimer-to-dimer (DD) transports, were postulated to determine the charge carrier conductivities of these molecules. The results highlight that the intermolecular electronic couplings and electrostatic interactions can significantly affect the stacking geometry, even in more extended structures; displaced stacks with smaller interlayer spacing resulted in more compact stacking and, thus, higher CT efficiency; face-to-face stacking geometries can help to reduce the energy gap and VDE. Despite the fact that common thiophene-based oligomers adopting edge-to-face herringbone motifs exhibited p-type (hole-transporting) characters, the face-to-face stacked models based on annelated β-trithiophenes exhibited remarkably increased n-type (electron-transporting) performances. The electric field in the z-direction produced a small influence on the DD charge transport, whereas both electron and hole mobilities decreased dramatically in the MM case. More importantly, in MM charge transport, the electric field increases the hole mobility so that it is higher than that of the electron.

Effect of pendant arm position and length on the structure and properties of nickel aromatic dicarboxylate coordination polymers incorporating a kinked organodiimine

Hydrothermal synthesis has afforded three nickel coordination polymers incorporating both aromatic dicarboxylates and the kinked and hydrogen bonding capable organodiimine 4,4′-dipyridylamine (dpa). These were characterized by single-crystal X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. [Ni(1,2-phda)(dpa)(H 2O)] n (1,2-phda = 1,2-phenylenediacetate, 1) displays (4,4) rhomboid grid-like 2D layers that aggregate into 3D through O–H⋯O hydrogen bonding. Shortening one of the pendant arms of the dicarboxylate ligand resulted in a shift to (6,3) herringbone style 2D coordination layer motifs in {[Ni(hmph)(dpa)] · 1.33H 2O} n (hmph = homophthalate, 2), which stack in an AA′B pattern. [Ni(1,3-phda)(dpa)(μ-H 2O) 0.5] n (1,3-phda = 1,3-phenylenediacetate, 3) manifests a canted primitive cubic type coordination polymer lattice constructed from dinuclear {Ni 2(μ-H 2O)} kernels linked into 3D through tethering 1,3-phda and dpa ligands. Analysis of the variable temperature magnetic susceptibility of 3 indicated the presence of antiferromagnetic superexchange within its dinuclear units ( g = 2.290(2), J = −4.21(2) cm −1).

Three polar derivatives of N-ethylcarbazole: materials for optical applications.

Three N-ethylcarbazole derivatives have been synthesized and tested for non-linear optical (NLO) properties. The compounds are 2-(9-ethyl-9H-carbazol-3-ylmethylene)malononitrile, C(18)H(13)N(3), (IIIa), 2-cyano-3-(9-ethyl-9H-carbazol-3-yl)thioacrylamide, C(18)H(15)N(3)S, (IIIb), and 3-(9-ethyl-9H-carbazol-3-yl)-2-(4-phenyl-1,3-thiazol-2-yl)acrylonitrile, C(26)H(19)N(3)S, (V). It was found that the molecules of (IIIa) and (V) are nearly planar, while non-planarity is more pronounced for (IIIb). Molecules of (IIIa) and (V) exhibit herring-bone packing motifs. In (IIIb), the molecules form layers coplanar with (-201), within which they form centrosymmetric dimers via N-H...S hydrogen bonds.

Sodium 3-methyl-4-nitrophenolate dihydrate: a crystal engineering route towards new herringbone structures for quadratic non-linear optics

Sodium 3-methyl-4-nitrophenolate dihydrate (Na3M4NP) is a new stable non-linear optical crystal of Cc monoclinic symmetry. The organic anions having an average calculated molecular hyperpolarisability β xxx ≈20×10 −30 esu are organised in a herringbone motif, inducing, together with water molecules, a very dense packing of NaO 6 edge shared octahedra. A three-dimensional network of homogeneous and short hydrogen bonds close-packs the herringbone motifs in a staggered arrangement. The crystal structure is simply described and explained in relation to basic inorganic structural models.

An organic–inorganic crystal for blue SHG: crystal growth and quadratic optical effect of 2-amino-5-nitropyridinium chloride

The effective quadratic coefficients 2-amino-5-nitropyridinium chloride (2A5NPCl) are measured by phase matched second harmonic generation. 2A5NPCl is an interesting material for quadratic nonlinear optics due to the quasi-optimized arrangement of 2A5NP units in herringbone motifs and the high density of nonlinear 2-amino-5-nitropyridinium chromophore per unit volume. The maximum effective coefficient is obtained as 9.7 pm/V at 1320 nm. Since 2A5NPCl crystal is transparent from 410 to 1650 nm, sum frequency generation is also carried out with incident beams of 1320 and 660 nm. In this study, 11% conversion efficiency from 660 to 440 nm is obtained for 1.6 mm interaction length.

Sodium 4-nitrophenolate 4-nitrophenol dihydrate crystal: a new herringbone structure for quadratic nonlinear optics

Sodium 4-nitrophenolate 4-nitrophenol dihydrate is a new nonlinear optical crystal of C2 monoclinic symmetry composed of two distinct organic chromophores of respective calculated molecular hyperpolarisabilities β xxx =18.2×10 –30 and 5.2×10 –30 esu. The chromophores are organised in herringbone motifs along inorganic chains of NaO6 edge shared octahedra. A short H-bond network assembles the herringbone motifs. A remarkable feature is the unique proton shared between the two chromophores respecting the twofold symmetry. The structure is isotypic with that of the magnesium bis(4-nitrophenolate) dihydrate. Structural analogies with other known metal nitrophenolates are pointed out and the nonlinear optical efficiency is discussed.

Organic-Inorganic Crystals for Optical Devices

AbstractTwo routes of crystal engineering and elaboration of optical materials are described. The former applied to the design of organic-inorganic crystals for quadratic nonlinear optics is supported by a strategy of deliberately engineered noncentrosymmetric structures built-up from herringbone motifs of 2-amino-5-nitropyridinium chromophore. The original crystal growth of a solid solution of a member of this family is presented and discussed. The latter is a simple and generic elaboration of stable organic nanocrystals embedded in sol-gel matrices. Several molecules and characterization techniques have been involved to demonstrate the validity of this preparation.

Arene–Arene Stacking in 6,6'-Diphenyl-3,3'-bi-1,2,4,5-tetrazine and 6-Phenyl-1,2,4,5-tetrazine-3-carbaldehyde Benzoylhydrazone Monohydrate

Despite the demands of the stronger hydrogen-bonding inter­actions present in the crystal structures of the title compounds, C16H10N8 and C16H12N6O.H2O, T-shaped and shifted π-stacked arrangements of aromatic moieties are preferred, leading to herringbone and/or π-stacked crystal-packing motifs. Therefore, in both these compounds the crystal packing is in accordance with the theory of arene–arene interactions being dominated by electrostatics.

Crystal Engineering of Noncentrosymmetric Structures Based on 2-Amino-5-nitropyridine and n-Chloroacetic Acid Assemblies

New noncentrosymmetric crystals including the 2-amino-5-nitropyridinium and 2-amino-5-nitropyridine chromophores have been designed following a strategy first applied to the 2-amino-5-nitropyridinium dihydrogen phosphate. If a counteranion able to self-aggregate in chains or layers as (H2PO4-)n is associated to the 2-amino-5-nitropyridinium cation, a noncentrosymmetric structure based on herringbone motifs is systematically formed. In the same way it has been observed that a bulky group grafted on the amine radical of the 2-amino-5-nitropyridine induces a noncentrosymmetric structure containing herringbone motifs of molecular entities. The structures of the 2-amino-5-nitropyridinium dichloroacetate ionic crystal and 2-amino-5-nitropyridine/chloroacetic acid cocrystal having respectively the P212121 and Cc symmetries confirm the validity of this strategy. The packings of these assemblies are discussed in terms of steric hindrance and hydrogen bonds. Powder samples of these materials exhibit second harmonic...

Structural evidence in 2-amino-5-nitropyridinium halides (Cl–, Br–) of herringbone motifs favourable to efficient quadratic non-linear optical properties

2-Amino-5-nitropyridinium halides have been synthesized and their crystal structures determined. The structures of acentric phases reveal networks of non-linear chromophores arranged in herringbone motifs. Their secondharmonic generation responses vary in magnitude between that of 3-methyl-4-nitropyridine N-oxide and 2-methyl-2,4-dinitrophenyl aminopropanoate molecular compounds. Chained anions screen favourably the interactions between the non-linear cations in acentric phases, while the reverse situation is observed in the centric phase of 2-amino-5-nitropyiridinium bromide built up with open pseudo-hexagonal anionic layers.