Lanthanum Lead Oxide Hydroxide Nitrates with a Nonlinear Optical Effect

Sr(NH2SO3)(NO3)·H2O: An Ultraviolet Nonlinear Optical Material Exhibiting Strong Second-Harmonic Generation Response and Sufficient Birefringence

Second-harmonic generation (SHG) response and birefringence stand as fundamental optical properties for nonlinear optical (NLO) materials. Up to now, engineering a strong SHG response and substantial birefringence in the sulfamate system has proven to be exceedingly challenging. A novel noncentrosymmetric compound, Sr(NH2SO3)(NO3)·H2O, has been meticulously designed by introducing the (NO3)- group characterized by significant polarizability anisotropy and hyperpolarizability into the polar non-π-conjugated (NH2SO3)- system. This compound exhibits a robust SHG response (5.2 × KDP), ample birefringence (0.077 at 546.1 nm), and a short ultraviolet (UV) absorption edge (290 nm). The linear and nonlinear optical properties can be attributed to the (NO3)- group and the (NH2SO3)- group. This study presents an effective approach that contributes to the design of more composite anionic UV NLO materials with excellent and balanced optical properties.

A butterfly-like lead-doped titanium-oxide compound with high performance in photocatalytic cycloaddition of CO2 to epoxide

The cycloaddition reaction of CO₂ to epoxides is quite promising for CO₂ capture and storage as well as the production of value-added fine chemicals. Herein, a novel atomically precise lead-doped titanium-oxide cluster with the formula Ti₁₀Pb₂O₁₆(phen)₄(Ac)₁₂(DMF)₂ (denoted as Ti10Pb2; phen = 1,10-phenanthroline; Ac = acetate; DMF = dimethylformamide) was synthesized through a facile solvothermal process, and is a molecular photocatalyst with surface-anchored main-group metal active sites. Its structure was characterized by single-crystal X-ray diffraction and other complementary techniques. Ti10Pb2 showed high photo-response and charge-separation efficiency under simulated sunlight irradiation. Ti10Pb2 was successfully used in the cycloaddition reaction of CO₂ with epoxides under solvent-free conditions. While its catalytic activity due to the Lewis acidity was moderate, simulated solar light irradiation further enhanced the reaction rate, demonstrating the synergistic effect of photocatalysis and Lewis-acid thermocatalysis.

Multifunctional Luminescent Sensor Based on the Pb2+ Complex Containing a Tetrazolato Ligand

A series of luminescent Pb²⁺ complexes, [Pb(L¹)₂]_n (1), [Pb(L²)₂]_n (2), [Pb(L³)(NO₃)(H₂O)₂]_n (3), [Pb(L³)(Br)(H₂O)]_n (4), [Pb(L³)(Cl)(H₂O)]_n (5), and [Pb(L⁴)(H₂O)₂] (6) have been synthesized by treatment of polydentate tetrazolato ligands with various hydrated Pb²⁺ salts (HL¹ = 2-(1H-tetrazol-5-yl)pyridine, HL² = 3-(1H-tetrazol-5-yl)isoquinoline, HL³ = 6-(1H-tetrazol-5-yl)-2,2'-bipyridine, and H₂L⁴ = 6,6'-bis(1H-tetrazol-5-yl)-2,2'-bipyridine). These complexes have been characterized by IR, TGA, and elemental analysis. Their crystal structures have been determined by X-ray crystallography, and the phase purity of bulk samples were further confirmed by PXRD. Their luminescence properties have been investigated in detail, and their emission origin may involve ligand-centered π-π* transition, metal-centered s-p transition and charge-transfer character. It is interesting to note that 5 exhibits obviously enhanced red-shifted emission, whose photoluminescence quantum yield (PLQY = 16.5%) is much higher than the other compounds (≤2%). Most importantly, the emission property of 5 was strongly affected by temperature. When the temperature rises from 295 to 493 K, the emission maximum gradually shifts to high energy due to the loss of the aqua ligand. In contrast, when the temperature is lowered from 295 to 13 K, two emission bands were observed. The low-energy emission band exhibits a slight blue shift, while a new high-energy emission band appears at around 520 nm, which is assigned to ligand-centered phosphorescence. After removal of the coordinated aqua ligand, the emission of 5-H₂O is very sensitive to the vapors of volatile primary amines and acids, although they have different response mechanisms. This result indicates that 5-H₂O may be a potential multifunctional sensor for temperature, volatile amines, and acids. To decipher the emission origin, DFT calculations have also been carried out based on the structure units of these compounds.

A(H3C3N3O3)(NO3) (A = K, Rb): Alkali-Metal Nitrate Isocyanurates with Strong Optical Anisotropy

The first alkali-metal nitrate isocyanurates, A(H₃C₃N₃O₃)(NO₃) (A = K, Rb), were synthesized by the tactic of introducing (NO₃)^- into isocyanurate with a mild hydrothermal technique. They crystallized into the same monoclinic centrosymmetric (CS) space group P2₁/c, which featured a 2D [(H₃C₃N₃O₃)(NO₃)]_∞ layered structure separated by K⁺ and Rb⁺ cations, respectively. Both compounds exhibited short ultraviolet cutoff edges (λ_cutoff = 228 and 229 nm) and large birefringences (Δn = 0.253 and 0.224 at 546.1 nm). More importantly, in comparison with most of the isocyanurates and nitrates, they have better thermal stability with decomposition temperatures up to 319.8 and 324.4 °C. In addition, our theoretical calculations reveal that the π-conjugated groups play significant roles in improving the optical anisotropy. Remarkably, introducing a π-conjugated inorganic acid radical (NO₃)^- into isocyanurate is an extremely meaningful strategy to explore new UV birefringent crystals.

Collaborative enhancement from Pb2+ and F− in Pb2(NO3)2(H2O)F2 generates the largest second harmonic generation effect among nitrates

The first metal nitrate fluoride nonlinear optical material, Pb₂(NO₃)₂(H₂O)F₂, was synthesized with a super strong second harmonic generation effect.

Connecting effect on the first hyperpolarizability of armchair carbon-boron-nitride heteronanotubes: pattern versus proportion

Carbon-boron-nitride heteronanotubes (BNCNT) have attracted a lot of attention because of their adjustable properties and potential applications in many fields. In this work, a series of CA, PA and HA armchair BNCNT models were designed to explore their nonlinear optical (NLO) properties and provide physical insight into the structure-property relationships; CA, PA and HA represent the models that are obtained by doping the carbon segment into pristine boron nitride nanotube (BNNT) fragments circularly around the tube axis, parallel to the tube axis and helically to the tube axis, respectively. Results show that the first hyperpolarizability (β0) of an armchair BNCNT model is dramatically dependent on the connecting patterns of carbon with the boron nitride fragment. Significantly, the β0 value of PA-6 is 2.00 × 10(4) au, which is almost two orders of magnitude larger than those (6.07 × 10(2) and 1.55 × 10(2) au) of HA-6 and CA-6. In addition, the β0 values of PA and CA models increase with the increase in carbon proportion, whereas those of HA models show a different tendency. Further investigations on transition properties show that the curved charge transfer from N-connecting carbon atoms to B-connecting carbon atoms of PA models is essentially the origin of the big difference among these models. This new knowledge about armchair BNCNTs may provide important information for the design and preparation of advanced NLO nano-materials.