Journal of Structural Chemistry最新文献

Optical-quality ZnWO₄:Eu³⁺ single crystals are grown by the low-gradient Čzochralski method. In a temperature range of 77-400 K, the ZnWO₄:Eu³⁺ single crystals exhibit intense red photoluminescence with CIE chromaticity coordinates (x = 0.614, y = 0.366) and a correlated color temperature of 1754 K. It is suggested that Eu³⁺-activated ZnWO₄ is a promising luminophore for the use in the phosphor-converted light-emitting diode technology.

Isomers of [5]helicene derivatives containing fluorenyl or tert-butylnitroxide radicals in positions 4 and 11 are studied by density functional theory simulations. It is shown that open forms of such isomers include two almost non-interacting unpaired electrons, while their cyclic forms exhibit diamagnetic states. The results obtained using two DFT functionals (M05-2X, B3LYP-D3BJ) are confirmed by multi-configurational SA-CASSCF/NEVPT2 calculations. A TD-DFT study of electronic spectra indicates the possibility of photoinduced switching between spin states of these compounds. The prospect of using [5]helicene as a platform for the design of organic magnetic switches is substantiated.

The structure of two nitrogen-containing heterocyclic analogs of mucochloric and mucobromic acids - 3,4-dichloro- and 3,4-dibromo-5-hydroxy-1,5-dihydro-2H-pyrrol-2-ones - is studied. It is established by XRD that the crystals of the two pyrrolinones are not isostructural, despite their similar molecular geometries and the same space group P2₁/c. On the contrary, the type of stereoisomeric recognition and, consequently, the crystal lattice architecture can be controlled by varying the halogen nature.

The Ce³⁺-doped optical quality Li_2–2xZn_2+x(MoO₄)₃ single crystals are grown by low-thermal-gradient Czochralski technique. Temperature dependences of PL (photoluminescence) and PLE (photoluminescence excitation) spectra, as well as decay curves are investigated and discussed in 77-300 K range in present article. The study confirmed that ultraviolet (UV) excitation is possible and calculated the CIE chromaticity coordinates, correlated color temperature (CCT), and color rendering index for the crystals.

Two compounds based on diiodoterephthalic and diiodoterphenyldicarboxylic acids [Ba(I₂TP)(DMF)] (2) and [Y(I₂TerPDC)(NO₃)(H₂O)(DMSO)]·DMSO (3) are prepared. The obtained single-crystal samples of 2 and 3 are studied by single crystal XRD. The performed structural analysis indicates that 2 and 3 contain halogen-halogen bonds and halogen-halogen contacts, respectively. The structure of the yttrium complex 3 is less dense than that of the barium complex 2. Also, one of the two DMSO molecules in 3 is not coordinated with the cation. The latter feature allows classifying the yttrium complex as a MOF, in contrast to the barium complex. The coordination numbers of barium and yttrium in these structures are 9 and 8, respectively, typically for these cations. The presence of iodinated ligands in MOFs can lead to the formation of halogen bonds with adsorbed molecules, thus possibly affecting the selectivity of the MOFs sorption properties.

Three regioisomers - 1,4-bis(indazol-1-yl)butane, 1-(indazol-1-yl)-4-(indazol-2-yl)butane, and 1,4-bis(indazol-2-yl)butane - are prepared by the reaction of indazole double alkylation by 1,4-dibromobutane in a KOH/DMSO superbasic medium. The main reaction product - 1,4-bis(indazol-1-yl)butane (1,4-binb) - is isolated in individual form by recrystallization from isopropyl alcohol. The binuclear arene-ruthenium complex [Ru₂Cl₄(1,4-binb)(p-cym)₂] is prepared using the obtained 1,4-bis(indazol-1-yl)butane. The structure of the studied compounds is confirmed by SC-XRD. According to the obtained XRD data, indazole rings adopt an anti-conformation relative to the linker, and dihedral angles at the nitrogen atoms of indazole rings are 180° both in the structure of 1,4-bis(indazol-1-yl)butane and in that of the corresponding arene-ruthenium complex.

Crystals of the new silicate K₃(Yb_0.84Nb_0.1□_0.06)[Si₃O₈(OH)₂] are synthesized hydrothermally at a temperature of 280 °C and a pressure of 100 atm. Its structure belongs to the known structure type of mixed layer silicates K₃RESi₃O₈(OH)₂, where RE = Y, Ho, Eu, Er Gd, Tb, Dy. The layers consist of chains of triorthogroups of Si tetrahedra that “embrace” isolated (Yb,Nb) octahedra. The K atoms are in and between the layers. The most interesting feature of the new crystals established for the first time is isomorphic incorporation of Nb atoms into the site occupied by Yb ions, which requires the presence of a vacancy at the octahedral position to compensate for the charge.

Protic ionic liquids (PILs) are promising candidates for electrochemical applications due to their wide liquid-state range, tunable physicochemical properties, and the possibility of controlling hydrogen-bond networks via molecular design. In this work, we report the synthesis and characterization of N,N-diethyl-octan-1-ammonium tetrafluoroborate selectively deuterated at the N–H site, [N₂₂₈D][BF₄]. The phase behavior and local hydrogen–bond structure were investigated by combining solid–state ²H nuclear magnetic resonance (NMR) spectroscopy and differential scanning calorimetry (DSC). DSC revealed the absence of a glass transition in the –120 °C to +150 °C interval, instead identifying multiple solid–solid transitions and a melting event via intermediate mesophases. Temperature-dependent ²H NMR spectra demonstrated the coexistence of two distinct hydrogen bonding environments in the solid phases (DQCC = 151-177 kHz and 129-140 kHz) at low and intermediate temperatures, with the transition to an isotropically mobile phase above 283 K. The ²H NMR evidenced the presence of the plastic phase above 283 K and enabled quantitative determination of transition thermodynamics (ΔH = 59 ± 8 kJ/mol; ΔS⁰ = 162 ± 25 J/(mol·K) to the state with mobile cations. The observed intermediate DQCC values reflect hydrogen-bond strengths in [BF₄]^– PILs and evidences multiple hydrogen–bonding geometries despite anion symmetry. These findings contribute to the understanding of structure–dynamics–phase behavior relationships in asymmetric cation PILs and may inform the design of optimized electrolytes for energy–related applications.

In the production of organic solar cells, carbon nanotubes serve as an additive, improving their performance, typically due to increased effective charge mobility in the active layer. However, the presence of metallic carbon nanotubes in the composition, causing active layer shunting and acting as a hole-electron recombination center, presents a challenge when carbon nanotubes are introduced into the active layer. We report the functionalization of multi-walled carbon nanotubes (MWCNTs) which partly converts their metallic behavior into semiconductor one. It is confirmed that nanohybrids consisting of fluorinated carbon nanotubes and isolated or semiconductor polymers can be potentially used to fine- tune the the active layer morphology in the organic solar cell.