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The hit compound 1,2,4-triazolo[4’,3’:2,3]pyridazino[4,5-b]indole 3 was synthesized from the reflux of 4-amino-5-indolyl-1,2,4-triazole-3-thione 1 with 4′-bromoacetophenone 2 in methanol catalyzed by concentrated HCl and the desired final molecule was obtained by recrystallization from methanol. The suggested structures of compounds 1 and 3 based on the spectral characterizations were confirmed by X-ray single crystal diffraction analysis. Compound 3 crystallized in the triclinic crystal system and P-1 space group with a = 5.9308(2) Å, b = 10.9695(3) Å, c = 14.7966(4) Å, α = 100.5010(10)°, β = 98.6180(10)°, and γ = 103.8180(10)°. On the other hand, the crystal system of 1 is monoclinic, where a = 6.23510(10) Å, b = 26.0156(4) Å, c = 12.4864(2) Å, β = 93.243(2)° and the space group is P21. The triazole and indole rings are found twisted from each other in both compounds. The twist angle is higher in 3 (12.65°) than 1 (4.94–7.22°). In the case of the former, the H…H (39.6%), H…C (22.0%), N…H (12.8%) and Br…H (13.2%) contacts are the most dominant while the C…C, C…H, Br…H, N…H and S…S contacts have the characteristics of strong interactions. In the latter, the C…H, N…H, S…H, S…S, and C…C contacts are the most important. In this case, the percentages of the H…H, C…H, N…H and S…H contacts are in the range of 34.9–37.4, 20.5–24.0, 12.2–13.6, 14.0–15.8, respectively. In both systems, the shape index and curvedness of surfaces confirmed the presence of π–π stacking interactions. peerReviewed

Funder: AiF Project, no: ZIM-KK5085302DF0, Funder: Polish National Agency for Academic Exchange within the Bekker programme (grant no. PPN/BEK/2020/1/00264/U/00001), Funder: Royal Society Te Apārangi and the Cambridge Commonwealth European and International Trust, Funder: Hans Fischer Senior Fellowship from the Technical University of Munich's Institute for Advanced Study, funded by the German Excellence Initiative, I-V-VI2 ternary chalcogenides are gaining attention as earth-abundant, nontoxic, and air-stable absorbers for photovoltaic applications. However, the semiconductors explored thus far have slowly-rising absorption onsets, and their charge-carrier transport is not well understood yet. Herein, we investigate cation-disordered NaBiS2 nanocrystals, which have a steep absorption onset, with absorption coefficients reaching >105 cm-1 just above its pseudo-direct bandgap of 1.4 eV. Surprisingly, we also observe an ultrafast (picosecond-time scale) photoconductivity decay and long-lived charge-carrier population persisting for over one microsecond in NaBiS2 nanocrystals. These unusual features arise because of the localised, non-bonding S p character of the upper valence band, which leads to a high density of electronic states at the band edges, ultrafast localisation of spatially-separated electrons and holes, as well as the slow decay of trapped holes. This work reveals the critical role of cation disorder in these systems on both absorption characteristics and charge-carrier kinetics.

Series of highly polar stilbene (1a–e), diphenylbutadiene (2a–c) and phenylethenylthiophene (3a–c) derivatives were prepared via Horner–Wadsworth–Emmons method with a view to produce new and efficient materials for second harmonic generation (SHG) in the solid-state. The single-crystal X-ray structures of compounds 1–3 reveal extensive polymorphism and a peculiar photodimerization of the 2-chloro-3,4-dimethoxy-4′-nitrostilbene derivative 1a to afford two polymorphs of tetra-aryl cyclobutane 4. The stilbene congeners 2-chloro-3,4-dimethoxy-4′-nitrostilbene (1a·non-centro), 5-bromo-2-hydroxy-3-nitro-4′-nitrostilbene (1b) and 4-dimethylamino-4′-nitrostilbene (1e), as well as 4′-fluoro-4′′-nitro-1,4-diphenyl-1,3-butadiene (2a) present the ideal, non-centrosymmetric arrangement of the chromophores for nonlinear optical (NLO) activity. Compounds 1b and 2a exhibit only relatively low intensity for second harmonic generation (0.04 and 0.18 times that of urea reference, respectively), while the stilbene polymorph 1a·non-centro shows NLO activity of over 32 times that of urea. In addition, the conjugated diaromatic compounds 1–3 display fluorescence behaviour in CH2Cl2 solutions with the exception of stilbene derivative 1b. peerReviewed

A new spirooxindole hybrid engrafted imidazo[2,1-b]thiazole core structure was designed and achieved via [3+2] cycloaddition reaction approach. One multi-component reaction between the ethylene derivative based imidazo[2,1-b]thiazole scaffold with 6-Cl-isatin and the secondary amine under heat conditions afforded the desired compound in a stereoselective manner. The relative absolute configuration was assigned based on single-crystal X-ray diffraction analysis. Hirshfeld calculations for 4 revealed the importance of the H . . . H (36.8%), H . . . C (22.9%), Cl . . . H (10.4%) and S . . . H (6.6%), as well as the O . . . H (4.7%), N . . . H (5.3%), Cl . . . C (1.6%), Cl . . . O (1.0%) and N . . . O (0.5%) contacts in the crystal stability. DFT calculations showed excellent straight-line correlations (R2 = 0.9776–0.9962) between the calculated and experimental geometric parameters. The compound has polar nature (3.1664 Debye). TD-DFT and GIAO calculations were used to assign and correlate the experimental UV-Vis and NMR spectra, respectively. peerReviewed

A new compounds named 3-4′-bipyrazoles 2 and 3 were synthesized in high chemical yield from a reaction of pyran-2,4-diketone 1 with aryl hydrazines under thermal conditions in MeOH. Compound 2 was unambiguously confirmed by single-crystal X-ray analysis. It crystalizes in a triclinic crystal system and space group P-1. Its crystal structure was found to be in good agreement with the spectral characterizations. With the aid of Hirshfeld calculations, the H…H (54.8–55.3%) and H…C (28.3–29.2%) intermolecular contacts are the most dominant, while the O…H (5.8–6.5%), N…H (3.8–4.6%) and C…C (3.0–4.9%) are less dominant. The compound has a polar nature with a net dipole moment of 6.388 Debye. The BD(2)C31-C32→BD*(2)N4-C34 (27.10 kcal/mol), LP(1)N5→BD*(2)C31-C32 (36.90 kcal/mol), BD(1)C32-C34→BD*(1)C18-C31 (6.78 kcal/mol) and LP(1)N4→BD*(1)N5-C31 (7.25 kcal/mol) are the strongest π→π*, n→π*, σ-σ* and n→σ* intramolecular charge transfer processes, respectively.

Crystallizing metal–organic frameworks (MOFs) has been studied using a tripodal pyridinecarboxylic acid derivative ligand and selected lanthanoid salts. The zwitterionic ligand, 1,1′,1′′-((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(pyridin-1-ium-4-carboxylate) (TTTPC) introduced as a bromide salt, forms coordination networks in aqueous environments and under ambient conditions with neodymium bromide, trifluoromethanesulfonate (OTf) or acetate (OAc). Seven structures are elucidated in detail using single crystal X-ray crystallography. TTTPC NdBr3, TTTPC NdBr2OTf, TTTPC NdBr(OTf)2 and TTTPC Nd(OTf)3 are porous 3D networks with similar ligand–metal and ligand–anion interactions, but with different anion distributions, coordination modes and/or crystal systems. Freshly prepared TTTPC NdBr2OAc is a porous 2D network, and otherwise has the same attributes, but it transforms into a 3D network upon drying. All network solids crystallize in the space group P[1 with combining macron] (# 2), except TTTPC NdBr(OTf)2 which crystallizes in P21/c (# 14). Compounds retain their crystallinity under vacuum, and a crystal structure for an evacuated sample of TTTPC NdBr2OTf is presented. Thermal analysis of network solids shows that upon heating, all solids exhibit solvent loss and withstand decomposition up to or over 300 °C. In addition to Nd networks, synthesis and crystal structures of several exactly or almost isostructural systems with other lanthanoids are presented. These include TTTPC YbBr3, TTTPC LnBr2OTf (Ln = La, Sm, Eu, Gd and Tb), TTTPC LnBr(OTf)2 (Ln = Sm, Eu, and Tb), TTTPC Yb(OTf)3 and TTTPC2Sm2(OTf)6. The synthesis and crystal structures of Ln(NO3)3 (Ln = La, Nd, and Y) are also briefly discussed as a separate, yet similar, system. Finally, a revised crystal structure of the protonated bromide TTTPC ligand, H2.5TTTPC, is suggested. peerReviewed

The title compound, poly[triaquabis[μ4-N,N′-(1,3,5-oxadiazinane-3,5-diyl)bis(carbamoylmethanoato)]dinickel(II)tetrapotassium], [K4Ni2(C7H6N4O7)2(H2O)3] n , is a second solvatomorph of poly[(μ4-N,N′-(1,3,5-oxadiazinane-3,5-diyl)bis(carbamoylmethanoato)nickel(II)dipotassium] reported previously [Plutenko et al. (2021). Acta Cryst. E77, 298–304]. The asymmetric unit of the title compound includes two structurally independent complex anions [Ni(C7H6N4O7)]2−, which exhibit an L-shaped geometry and consist of two almost flat fragments perpendicular to one another: the 1,3,5-oxadiazinane fragment and the fragment including other atoms of the anion. The central Ni atom is in a square-planar N2O2 coordination arrangement formed by two amide N and two carboxylate O atoms. In the crystal, the title compound forms a layered structure in which layers of negatively charged complex anions and positively charged potassium cations are stacked along the a-axis direction. The polymeric framework is stabilized by a system of hydrogen-bonding interactions in which the water molecules act as donors and the carboxylic, amide and water O atoms act as acceptors.

We describe a three-dimensional crystalline topological insulator (TI) phase of matter that exhibits spontaneous polarization. This polarization results from the presence of (approximately) flat bands on the surface of such TIs. These flat bands are a consequence of the bulk-boundary correspondence of polarized topological media, and contrary to related nodal line semimetal phases also containing surface flat bands, they span the entire surface Brillouin zone. We also present an example Hamiltonian exhibiting a Lifshitz transition from the nodal line phase to the TI phase with polarization. Utilizing elasticity tetrads, we show a complete classification of 3D crystalline TI phases and invariants. The phase with polarization naturally arises from this classification as a dual to the previously better-known 3D TI phase exhibiting quantum (spin) Hall effect. Besides polarization, another implication of the large surface flat band is the susceptibility to interaction effects such as superconductivity: the mean-field critical temperature is proportional to the size of the flat bands, and this type of systems may hence exhibit superconductivity with a very high critical temperature., 10 pages, 4 figures; new presentation and discussion

Unravelling the rules of molecular motion is a contemporary challenge that promises to support the development of responsive materials and is likely to enhance the understanding of functional motion. Advances in integrating light‐driven molecular motors in soft matter have led to the design and realization of chiral nematic (cholesteric) liquid crystals that can respond to light with modification of their helical pitch, and also with helix inversion. Under illumination, these chiral liquid crystals convert from one helical geometry to another. Here, a series of light‐driven molecular motors that feature a rich configurational landscape is presented, specifically which involves three stable chiral states. The succession of chiral structures involved in the motor cycle is transmitted at higher structural levels, as the cholesteric liquid crystals that are formed can interconvert between helices of opposite handedness, reversibly. In these materials, the dynamic features of the motors are thus expressed at the near‐macroscopic, functional level, into addressable colors that can be used in advanced materials for tunable optics and photonics. peerReviewed

International audience; Magnets derived from inorganic materials (e.g., oxides, rare-earth–based, and intermetallic compounds) are key components of modern technological applications. Despite considerable success in a broad range of applications, these inorganic magnets suffer several drawbacks, including energetically expensive fabrication, limited availability of certain constituent elements, high density, and poor scope for chemical tunability. A promising design strategy for next-generation magnets relies on the versatile coordination chemistry of abundant metal ions and inexpensive organic ligands. Following this approach, we report the general, simple, and efficient synthesis of lightweight, molecule-based magnets by postsynthetic reduction of preassembled coordination networks that incorporate chromium metal ions and pyrazine building blocks. The resulting metal-organic ferrimagnets feature critical temperatures up to 242°C and a 7500-oersted room-temperature coercivity.

Sulfur is a widely used halogen bond (XB) acceptor, but only a limited number of neutral XB acceptors with bifurcated sp3-S sites have been reported. In this work a new bidentate XB acceptor, 1-(4-pyridyl)-4-thiopyridine (PTP), which combines sp3-S and sp2-N acceptor sites, is introduced. Three halogen bonded cocrystals were obtained by using 1,4-diiodobenzene (DIB), 1,4-diiodotetrafluorobenzene (DIFB), and iodopentafluorobenzene (IPFB) as XB donors and PTP as acceptor. The structures of the cocrystals showed some XB selectivity between the S and N donors in PTP. However, the limited contribution of XB to the overall molecular packing in these three cocrystals and the results from DSC measurements clearly point out the synergetic influence and interplay of all noncovalent interactions in crystal packing of these compounds.

International audience; 3-(Phenyl)-1-(pyrid-2-yl)-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl (2) demonstrates the first example of polymorphism in the family of Blatter radicals. Two polymorphs, 2α and 2β, have been identified and characterized by single crystal X-ray diffractometry and magnetic susceptibility measurements to investigate their magnetism–structure correlations. Both polymorphs form one-dimensional (1D) π stacks of evenly spaced radicals with distinctly different π–π overlap modes. Within the 1D π stacks, radicals are located at evenly interplanar distances, 3.461 Å for 2α and 3.430 Å for 2β. Magnetic susceptibility studies indicate that both polymorphs exhibit antiferromagnetic interactions inside their 1D π stacks. The magnetic susceptibility data are best interpreted in terms of a regular chain model of antiferromagnetically coupled quantum spins (H = -Σi Si.Si+1) with exchange-interactions of J/kB = −36.7(3) K (−25.5(2) cm−1) for 2α and J/kB = −72(3) K (−50(2) cm−1) for 2β. For polymorph 2β, a crossover on the magnetic susceptibility around 20 K suggests the presence of a phase transition, which might be related to dimerization of the radicals along the chain. DFT calculations support the experimental structure–magnetism results and the antiferromagnetic nature of the local interactions between radicals within the 1D π stacks.

European journal of organic chemistry : EurJOC 2020(38), 6073-6077 (2020). doi:10.1002/ejoc.202001008, Published by Wiley-VCH Verl., Weinheim

A systematic analysis using single crystal X-ray diffraction was performed to explore the role exerted by potential intercomponent proton-transfer reactions in the supramolecular structures of A–B cocrystals formed by 5-haloderivatives of uracil (A), coupled with 2-aminoadenine simulants (aminoazines, B). Twelve new heterodimers were synthesized in different stoichiometries and cocrystallized by solvent cogrinding followed by solution crystallization. In the binary cocrystals, uracil or 1-methyluracil with halide modification at the 5 position (F, Cl, Br, I) was coupled with amino-aromatic N-heterocycles (melamine, 2,4,6-triaminopyrimidine, 2,6-diaminopyridine) as a multivalent site for pyrimidine nucleobase recognition. The crystallographic analysis showed that, next to the expected neutral three-point hydrogen bonds (TPI), ionized TPI, favored by A → B proton transfer, can be used for WC multifacial recognition. Noteworthy, the formation of the charged TPI, which depends on the acid/base properties of the components, always takes place between the more acidic site of the 5-halonucleobases (N3 atom) and the more basic site (imino N atom) of 2,4,6-triaminopyrimidine or 2,6-diaminopyridine, and melamine recognition unit results in being insufficiently basic to accept a proton. The general ability of pyrimidine nucleobases to provide electron donating groups to halogen bonding has been confirmed in seven cocrystals containing the 5-chloro, 5-bromo, or 5-iododerivatives coupled with melamine or 2,4,6-triaminopyrimidine. Considerations of the relative acidities of coformers A and of the relative basicities of coformers B allowed us to design and characterize by single-crystal X-ray diffraction the first ternary pyrimidine nucleobase-containing cocrystal based on the JANUS-WEDGE concept: the nucleobase–Janus–nucleobase (1:1:1) triad showing a 2,4,6-triamino pyrimidine molecule wedged via neutral and ionized TPI between the 5-fluorouracil/1-methyluracil pair in reverse WC fashion. peerReviewed

Controlling thermal transport at the nanoscale is vital for many applications. Previously, it has been shown that this control can be achieved with periodically nanostructured two-dimensional phononic crystals for the case of suspended devices. Here, we show that thermal conductance can also be controlled with three-dimensional phononic crystals, allowing the engineering of the thermal contact of more varied devices without the need for suspension in the future. We show the experimental results obtained at sub-Kelvin temperatures for two different period three-dimensional crystals and for a bulk control structure. The results show that the conductance can be enhanced with the phononic crystal structures in our geometry. This result cannot be fully explained by the simplest theory taking into account the coherent modification of the phonon band structure, calculated by finite element method simulations. peerReviewed

Intra and intermolecular interactions found in the developed crystals of the synthesized py-ron-2,4-dione derivatives play crucial rules in the molecular conformations and crystal stabili-ties, respectively. In this regard, Hirshfeld calculations were used to quantitatively analyze the different intermolecular interactions in the crystal structures of some functionalized py-ran-2,4-dione derivatives. The X-ray structure of pyran-2,4-dione derivative namely (3E,3′E)-3,3′-((ethane-1,2-diylbis(azanediyl))bis(phenylmethanylylidene))bis(6-phenyl-2H-pyran-2,4(3H)-dione) was determined. It crystallized in the monoclinic crystal system and C2/c space group with unit cell parameters: a = 14.0869(4) Å, b = 20.9041(5) Å, c = 10.1444(2) Å and β = 99.687(2)°. Generally, the H…H, H…C, O…H and C…C contacts are the most important interactions in the molecular packing of the studied pyran-2,4-diones. The molecular structure of these compounds is stabilized by intramolecular O…H hydrogen bond. The nature and strength of the O…H hy-drogen bonds were analyzed using atoms in molecules calculations. In all compounds, the O…H hydrogen bond belongs to closed-shell interactions where the interaction energies are higher at the optimized geometry than the X-ray one due to the shortening in the A…H distance as a con-sequence of the geometry optimization. These compounds have polar characters with different charged regions which explored using molecular electrostatic potential map. Their natural charges, reactivity descriptors and NMR chemical shifts were computed, discussed and compared.

We describe the use of dicyanoaurate ions as linear ditopic metal–organic acceptors for the halogen bond-driven assembly of a dichroic metal–organic cocrystal based on azobenzene chromophores. Structural analysis by single crystal X-ray diffraction revealed that the material is a four-component solid, consisting of anticipated anionic metal–organic halogen-bonded chains based on dicyanoaurate ions, as well as complex potassium-based cations and discrete molecules of the crown ether 15-crown-5. Importantly, the structural analysis revealed the parallel alignment of the halogen-bonded chains required for dichroic behaviour, confirming that crystal engineering principles developed for the design of halogen-bonded dichroic organic cocrystals are also applicable to metal-based structures. In the broader context of crystal engineering, the structure of the herein reported dichroic material is additionally interesting as the presence of an ion pair, a neutral azobenzene and a molecule of a room-temperature liquid make it an example of a solid that simultaneously conforms to definitions of a salt, a cocrystal, and a solvate.

The host-guest complexes of C-propyl-2-bromoresorcinarene with pyridine N-oxide, 3-methylpyridine N-oxide, quinoline N-oxide and isoquinoline N-oxide are studied using single crystal X-ray crystallography and 1H NMR spectroscopy. The C-propyl-2-bromoresorcinarene forms endo-complexes with the aromatic N-oxides in the solid-state when crystallised from either methanol or acetone. In solution, the endo-complexes were observed only in methanol-d4. In DMSO the solvent itself is a good guest, and crystallisation provides only solvate endo-complexes. The C-propyl-2-bromoresorcinarene shows remarkable flexibility when crystallised from either methanol or acetone, and packs into one-dimensional self-included chains. Of special note, crystallising C-propyl-2-bromoresorcinarene with 3-methylpyridine N-oxide from acetone results in a 2:2 dimeric capsular assembly organised through both C−H···πhost and N−O···(H−O)host interactions. peerReviewed

The crystal growth of potassium iodide was controlled by using the neutral organic 1,1′-bis(pyridin-4-ylmethyl)-2,2′-biimidazole (L) ligand as a modifier. The selected modifier allows the preservation of original cubic [K4I4] units and their arrangement into a linear ligand-supported 1D chain. The supported [K4I4] cubes are only slightly distorted compared to the cubes found in pure KI salt. The N–K binding of the ligand to the KI salt, as well as weak I⋯H, N⋯H, and N⋯I interactions, stabilizes the structure to create a unique 1D polymer of neutral potassium iodide ionic salt inside the [K4I4L4]n complex.

True trimorphic cocrystals, i.e. multi-component molecular crystals of identical composition that exhibit three polymorphic structures, are exceedingly rare and so far no halogen-bonded cocrystal system has been reported to exhibit trimorphism. Here we describe a unique example of a trimorphic cocrystal exhibiting both hydrogen and halogen bonds in which the differences between polymorphs reveal their orthogonality, evident by the apparently independent variation of well-defined hydrogen- and halogen-bonded motifs. peerReviewed

The ruthenium carbonyl compounds, Ru(bpy)(CO)2X2 (X = Cl, Br or I) act as neutral halogen bond (XB) acceptors when co-crystallized with 1,4-diiodotetrafluoro-benzene (DITFB). The halogen bonding strength of the Ru-X&sdot, &sdot, I halogen bonds follow the nucleophilic character of the halido ligand. The strongest halogen bond occurs between the chlorido ligand and the iodide atoms of the DITFB. All three halogen bonded complexes form polymeric assemblies in the solid state. In Ru(bpy)(CO)2Cl2&sdot, DITFB (1) and in Ru(bpy)(CO)2Br2&sdot, DITFB (2) both halido ligands are halogen bonded to only one DITFB donor. In Ru(bpy)(CO)2I2&sdot, DITFB (3) only one of the halido ligands is involved in halogen bonding acting as ditopic center for two DITFB donors. The polymeric structures of 1 and 2 are isomorphic wave-like single chain systems, while the iodine complexes form pairs of linear chains attached together with weak F&sdot, O&equiv, C interactions between the closest neighbors. The stronger polarization of the iodide ligand compared to the Cl or Br ligands favors nearly linear C-I&sdot, I angles between the XB donor and the metal complex supporting the linear arrangement of the halogen bonded chain.

The exceptional performance of oxobenzene-bridged bis-1,2,3-dithiazolyls 6 as single-component neutral radical conductors arises from the presence of a low-lying π-lowest unoccupied molecular orbital, which reduces the potential barrier to charge transport and increases the kinetic stabilization energy of the metallic state. As part of ongoing efforts to modify the solid-state structures and transport properties of these so-called multiorbital materials, we report the preparation and characterization of the acetoxy, methoxy, and thiomethyl derivatives 6 (R = OAc, OMe, SMe). The crystal structures are based on ribbonlike arrays of radicals laced together by S···N' and S···O' secondary bonding interactions. The steric and electronic effects of the exocyclic ligands varies, affording one-dimensional (1D) π-stacked radicals for R = OAc, 1D cofacial dimer π-stacks for R = SMe, and a pseudo two-dimensional (2D) brick-wall arrangement for R = OMe. Variable-temperature magnetic and conductivity measurements reveal strong antiferromagnetic interactions and Mott insulating behavior for the two radical-based structures (R = OAc, OMe), with lower room-temperature conductivities (σRT ≈ 1 × 10-4 and ∼1 × 10-3 S cm-1, respectively) and higher thermal activation energies ( Eact = 0.24 and 0.21 eV, respectively) than found for the ideal 2D brick-wall structure of 6 (R = F), where σRT ≈ 1 × 10-2 S cm-1 and Eact = 0.10 eV. The performance of R = OMe, OAc relative to that of R = F, is consistent with the results of density functional theory band electronic structure calculations, which indicate a lower kinetic stabilization energy of the putative metallic state arising from their reduced electronic dimensionality.

The exceptional performance of oxobenzene-bridged bis-1,2,3-dithiazolyls 6 as single-component neutral radical conductors arises from the presence of a low-lying π-lowest unoccupied molecular orbital, which reduces the potential barrier to charge transport and increases the kinetic stabilization energy of the metallic state. As part of ongoing efforts to modify the solid-state structures and transport properties of these so-called multiorbital materials, we report the preparation and characterization of the acetoxy, methoxy, and thiomethyl derivatives 6 (R = OAc, OMe, SMe). The crystal structures are based on ribbonlike arrays of radicals laced together by S···N′ and S···O′ secondary bonding interactions. The steric and electronic effects of the exocyclic ligands varies, affording one-dimensional (1D) π-stacked radicals for R = OAc, 1D cofacial dimer π-stacks for R = SMe, and a pseudo two-dimensional (2D) brick-wall arrangement for R = OMe. Variable-temperature magnetic and conductivity measurements reveal strong antiferromagnetic interactions and Mott insulating behavior for the two radical-based structures (R = OAc, OMe), with lower room-temperature conductivities (σRT ≈ 1 × 10–4 and ∼1 × 10–3 S cm–1, respectively) and higher thermal activation energies (Eact = 0.24 and 0.21 eV, respectively) than found for the ideal 2D brick-wall structure of 6 (R = F), where σRT ≈ 1 × 10–2 S cm–1 and Eact = 0.10 eV. The performance of R = OMe, OAc relative to that of R = F, is consistent with the results of density functional theory band electronic structure calculations, which indicate a lower kinetic stabilization energy of the putative metallic state arising from their reduced electronic dimensionality. peerReviewed

The major diastereomer formed in the Barbier-type metal-mediated allylation of D-mannose has previously been shown to adopt a perfectly linear conformation, both in solid state and in solution, resulting in the formation of hydrogen-bonded networks and subsequent aggregation from aqueous solution upon stirring. Here, a comprehensive study of the solid state structure of both the allylated D-mannose and its racemic form has been conducted. The binary melting point diagram of the system was determined by differential scanning calorimetry analysis, and the obtained results, along with structure determination by single crystal X-ray diffraction, confirmed that allylated mannose forms a true racemate. Further examination by powder X-ray diffraction and CP MAS 13C NMR spectroscopy revealed polymorphism both in the pure enantiomer and in the racemate. In addition, the propargylated and hydrogenated analogues of allylated D-mannose were prepared and subjected to thermal and spectroscopic analyses. The crystal structure of the propargylated compound was successfully determined, showing a linear molecular conformation similar to that found for allylated D-mannose. Both new compounds likewise display aggregation behavior in water, further verifying that the low-energy linear conformation plays a significant role in this unusual behavior of these rodlike mannose derivatives. peerReviewed

Light scattering by particles large compared to the wavelength of incident light is traditionally solved using ray optics which considers absorption inside the particle approximately, along the ray paths. To study the effects rising from this simplification, we have updated the ray-optics code SIRIS to take into account the propagation of light as inhomogeneous plane waves inside an absorbing particle. We investigate the impact of this correction on traditional ray-optics computations in the example case of light scattering by ice crystals through the extended near-infrared (NIR) wavelength regime. In this spectral range, ice changes from nearly transparent to opaque, and therefore provides an interesting test case with direct connection and applicability to atmospheric remote-sensing measurements at NIR wavelengths. We find that the correction for inhomogeneous waves systematically increases the single-scattering albedo throughout the NIR spectrum for both randomly-oriented, column-like hexagonal crystals and ice crystals shaped like Gaussian random spheres. The largest increase in the single-scattering albedo is 0.042 for hexagonal crystals and 0.044 for Gaussian random spheres, both at λ = 2.725 µm. Although the effects on the 4 × 4 scattering-matrix elements are generally small, the largest differences are seen at 2.0 µm and 3.969 µm wavelengths where the correction for inhomogeneous waves affects mostly the backscattering hemisphere of the depolarization-connected P22/P11, P33/P11, and P44/P11. We evaluated the correction for inhomogeneous waves through comparisons against the discrete exterior calculus (DEC) method. We computed scattering by hexagonal ice crystals using the DEC, a traditional ray-optics code (SIRIS3), and a ray-optics code with inhomogeneous waves (SIRIS4). Comparisons of the scattering-matrix elements from SIRIS3 and SIRIS4 against those from the DEC suggest that consideration of the inhomogeneous waves brings the ray-optics solution generally closer to the exact result and, therefore, should be taken into account in scattering by absorbing particles large compared to the wavelength of incident light.

[TiCp2S5] (phase A), [TiCp2Se5] (phase F), and five solid solutions of mixed titanocene selenide sulfides [TiCp2SexS5−x] (Cp = C5H5−) with the initial Se:S ranging from 1:4 to 4:1 (phases B–E) were prepared by reduction of elemental sulfur or selenium or their mixtures by lithium triethylhydridoborate in thf followed by the treatment with titanocene dichloride [TiCp2Cl2]. Their 77Se and 13C NMR spectra were recorded from the CS2 solution. The definite assignment of the 77Se NMR spectra was based on the PBE0/def2-TZVPP calculations of the 77Se chemical shifts and is supported by 13C NMR spectra of the samples. The following complexes in varying ratios were identified in the CS2 solutions of the phases B–E: [TiCp2Se5] (51), [TiCp2Se4S] (41), [TiCp2Se3S2] (31), [TiCp2SSe3S] (36), [TiCp2SSe2S2] (25), [TiCp2SSeS3] (12), and [TiCp2S5] (01). The disorder scheme in the chalcogen atom positions of the phases B–E observed upon crystal structure determinations is consistent with the spectral assignment. The enthalpies of formation calculated for all twenty [TiCp2SexS5−x] (x = 0–5) at DLPNO-CCSD(T)/CBS level including corrections for core-valence correlation and scalar relativistic, as well as spin-orbit coupling contributions indicated that within a given chemical composition, the isomers of most favourable enthalpy of formation were those, which were observed by 77Se and 13C NMR spectroscopy.

This thesis focuses on studying phononic crystal structures. More specifically, it is aimed at fabrication and measurement of thermal properties of two-dimensional (2D) periodic microstructures and three-dimensional (3D) nanostructures. There is great interest in understanding, manipulating and considering application perspective of minimizing of thermal transport in periodic structures. Periodic structures have been studied more on their optical properties, but this thesis places emphasis on their application of manipulating heat. A process of fabricating two-dimensional hole array phononic (2D PnC) structures is described here. It consists of membrane preparation, superconductor-insulatornormal metal-insulator-superconductor (SINIS) tunnel junction fabrication and etching of 2D PnC structures. Simple square array geometries of periods 4, 8, 16 m were fabricated, keeping filling factor of holes as 0.7. Thermal conductance of phononic structures with the three different periods were measured and compared with uncut membranes at temperatures from 50 mK to 1.2 K. All PnC structures gave a lower thermal conductance than membrane. In addition, thermal conductance was measured on membranes by different types of SINIS junction pairs. The variables were the geometry, the normal metal material and the normal metal length, which all affected the measured result. It is thus important to keep the SINIS heaters and thermometers the same when studying thermal conductance and its dependence on the period of the PnC structure. Additionally, sometimes superconductor-normal metalsuperconductor (SNS) junction pairs were accidentally made. Thermal conductance measured using a SNS structure as a heater and SINIS structure as a thermometer is also shown. We also address the fabrication of 3D colloidal polystyrene(PS) nano-sphere PnC structures on plain chips and the statistics of the deposition process, selfassembly by vertical dipping. Combinations of dipping angle of 45 and 90 , withdrawal speed of 0.01 mm/min to 0.05 mm/min and nano-sphere colloidal solution concentration of 0.02%, 0.2%, 2%, 5% and 10% were studied. Colloidal 3D PnC structure of face-centered cubic (fcc) crystal domains were self-assembled. Silicon chips with etched microscale boxes were fabricated and dipped vertically into 10% concentration PS colloidal solution at withdrawal at speed of 0.01 mm/min to 0.04 mm/min. Lower speed, higher concentration and 90 vertical dipping produce larger 3D PnC domain sizes on average. It was found that one big domain could fill a 20 m deep confined box no larger than 200 m length. However, there were always cracks between the domains and the edges of the box. Therefore, a polymer box was developed and used instead as a confinement box. It was fabricated by three dimensional lithography (3DL), using two types of resist: IPL 780 and IPDIP. Glass substrates with 10 m high IPL780 resist polymer boxes of hollow area of 100 m 100 m were dipped into a solution of 0.5%, 1% and 2% concentration of 260 nm diameter polystyrene nano-spheres at withdrawal speed of 0.01 and 0.02 mm/min. Only the sample with 1% concentration at withdrawal speed of 0.01 mm/min gave good results. There were no PS nano-sphere self-assembled on top of IPL780 box. However, there were several domains inside one box. So, a 20 m high polymer box of 50 m 50 m area was fabricated on silicon chips. They were dipped into a PS nano-sphere solution of 1%, 2 % and 5 % concentration at the speed of 0.01 mm/min. Finally, a method was also developed to protect PS colloidal PnC structures from deformation and dissolution. As expected, there was only one domain inside the box formed from the concentration of 1%. Unexpected, there were PS nano-spheres also on top of the sides of IPDIP boxes. PnC structures were treated by e-beam irradiation and protected by a capping layer of AlOx. Aluminum wires were successfully deposited on top of the PnC structures, which is promising for mounting thermal conductance measurement devices on top.