Synthesis and Crystal Structures of Two New Oxaspirocyclic Compounds

Crystal Structure, Photophysical Study, Hirshfeld Surface Analysis, and Nonlinear Optical Properties of a New Hydroxyphenylamino Meldrum's Acid Derivative

The structural, photophysical, and vibrational properties of a new hydroxyphenylamino Meldrum's acid derivative, 3-((2-hydroxyphenylamino)methylene)-1,5-dioxaspiro[5.5]undecane-2,4-dione (HMD), were studied. The comparison of experimental and theoretical vibrational spectra can help understand basic vibration patterns and provides a better interpretation of IR spectra. The UV-Vis spectrum of HMD was computed using density functional theory (DFT)/B3LYP/6-311 G(d,p) basis set in the gas state, and the maximum wavelength was in accord with the experimental data. The molecular electrostatic potential (MEP) and Hirshfeld surface analysis confirmed O(1)-H(1A)···O(2) intermolecular hydrogen bonds in the HMD molecule. The natural bond orbital (NBO) analysis provided delocalizing interactions between π→π* orbitals and n→σ*/π* charge transfer transitions. Finally, the thermal gravimetric (TG)/differential scanning calorimeter (DSC) and the non-linear optical (NLO) properties of HMD were also reported.

An Organometallic Gold(III) Reagent for 18F Labeling of Unprotected Peptides and Sugars in Aqueous Media

The ¹⁸F labeling of unprotected peptides and sugars with a Au(III)-[¹⁸F]fluoroaryl complex is reported. The chemoselective method generates ¹⁸F-labeled S-aryl bioconjugates in an aqueous environment in 15 min with high radiochemical yields and displays excellent functional group tolerance. This approach utilizes an air and moisture stable, robust organometallic Au(III) complex and highlights the versatility of designer organometallic reagents as efficient agents for rapid radiolabeling.

The crystal structure of 3-(4-hydroxybenzyl)-1,5-dioxaspiro[5.5]undecane-2,4-dione, C16H18O5

C16H18O5, monoclinic, P21/c (no. 14), a = 11.281(2) Å, b = 12.321(3) Å, c = 10.630(2) Å, β = 101.07(3)°, V = 1450.1(5) Å3, Z = 4, R gt(F) = 0.0421, wR ref(F 2) = 0.1123, T = 293(2) K.

The crystal structure of 3-((phenylamino)methylene)-1,5-dioxaspiro[5.5]undecane-2,4-dione, C16H17N1O4

C16H17N1O4, triclinic, P1̅ (no. 2), a = 7.0971(3) Å, b = 7.6638(4) Å, c = 13.2375(6) Å, α = 92.116(10)°, β = 99.690(10)°, γ = 95.196(10)° V = 705.81(6) Å3, Z = 2, R gt(F) = 0.0529, wR ref(F 2) = 0.1489, T = 296(2) K.

Synthesis and Crystal Structure of a New Hydrated Benzimidazolium Salt Containing Spiro Structure

A new hydrated benzimidazolium salt containing spiro structure was obtained when benzimidazole is added to ethyl alcohol of 1,5-dioxaspiro[5.5]undecane-2,4-dione and trimethoxymethane. The title compound (C19H21O8) (C7H7N2) (0.5H2O) was characterized by elemental analysis, IR, UV-Vis, and single-crystal X-ray diffraction. The result shows that it belongs to the triclinic system, space group P-1, with a = 11.017(2) Å, b = 11.424(2) Å, c = 11.650(2) Å, α = 70.60(3)°, β = 71.00(3)°, γ = 67.64(3)°, Mr = 505.51, V = 1245.2(5) Å, Z = 2, Dc = 1.348 g/cm3, F(000) = 534, μ(MoKa) = 0.102 mm−1. There exist two types of hydrogen bonds in the crystal. (C19H21O8)− anions and (C7H7N2)+ cations are linked by N–H···O hydrogen bonds, while (C19H21O8)− anions and free water are linked by O–H···O hydrogen bonds. All of the above hydrogen bonds form a one-dimensional (1D)-chained structure. The 1D chains further links the molecule into a three-dimensional (3D)-layered structure.