Assembly of 6-aminonicotinic acid and inorganic anions into different dimensionalities: Crystal structure, absorption properties and Hirshfeld surface analysis

Enhanced Coplanarity and Giant Birefringence in Hydroxypyridinium Nitrate via Hydrogen Bonding between Planar Donors and Planar Acceptors

Birefringent crystals, which possess optical anisotropy, are important optical components. However, designing and synthesizing birefringent crystals faces the challenge of achieving anisotropic structures, especially coplanar geometries. Herein, we achieve a significant birefringence in an ionic compound (C5H6ON)+(NO3)-, (4-hydroxypyridinium nitrate, 4HPN) by hydrogen bonding between planar donors and planar acceptors. We demonstrate that the interactions between the planar hydrogen bond donor ((C5H6ON)+) and planar hydrogen bond acceptor ((NO3)-) ensure the coplanarity during the crystal packing, generating the desired giant optical anisotropy. On two manually cut crystal chips, we observe aΔ n o b v . ${\Delta {n}^{obv.}}$ =0.494 (Δ n m a x c a l . ${\Delta {n}_{max}^{cal.}}$ =0.593), which is the largest among nitrates, or hydroxypyridinium derivatives. ThisΔ n o b v . ${\Delta {n}^{obv.}}$ value already surpasses those of the benchmark crystals, e.g., YVO4 and CaCO3, commonly used in the UV to visible and near IR spectral range. 4HPN also exhibits a strong second harmonic generation response (9.55×KDP). This strategy offers a promising avenue for the design and development of birefringent crystals with potential applications in optical communication, sensing and signal processing devices.

The crystal structure of 3-amino-5-carboxypyridin-1-ium iodide, C6H7IN2O2

C6H7BrN2O2, triclinic, P 1 ‾ $\overline{1}$ (no. 2), a = 7.4522(4) Å, b = 7.4741(5) Å, c = 8.3144(5) Å, α = 90.036(3)°, β = 99.808(3)°, γ = 117.724(2)°, V = 402.25(4) Å3, Z = 2, R gt (F) = 0.0156, wR ref (F 2) = 0.0367, T = 150.0 K.

The crystal structure of 2-amino-5-carboxypyridin-1-ium iodide monohydrate, C6H9IN2O3

C6H9IN2O3, monoclinic, P 2 1 / c $P{2}_{1}/c$ (no. 14), a = 9.3654(2) Å, b = 8.0312(2) Å, c = 12.7668(3) Å, β = 107.825(1)°, V = 914.16(4) Å3, Z = 4, R gt (F) = 0.0156, wR ref (F 2) = 0.0354, T = 150(2) K.

Halogen-bonding contacts determining the crystal structure and fluorescence properties of organic salts

Different inorganic anions tuning halogen-bonding contacts to form different 3D networks with various absorption and emission properties.

Substituent swap affects the crystal structure and properties of N-benzyl-4-amino-1,2,4-triazole related organic salts

Different inorganic anions bridging the ligands to form structurally different 3-D frameworks, which vary in π⋯π stacking motifs, solubilities, and thermogravimetric and emission properties, are reported.