Poly[diaqua-tris(μ(4)-isophthalato)dilanthanum(III)]

Picosecond sulfur K-edge X-ray absorption spectroscopy with applications to excited state proton transfer

Picosecond X-ray absorption (XA) spectroscopy at the S K-edge (∼2.4 keV) is demonstrated and used to monitor excited state dynamics in a small organosulfur molecule (2-Thiopyridone, 2TP) following optical excitation. Multiple studies have reported that the thione (2TP) is converted into the thiol (2-Mercaptopyridine, 2MP) following photoexcitation. However, the timescale and photochemical pathway of this reaction remain uncertain. In this work, time-resolved XA spectroscopy at the S K-edge is used to monitor the formation and decay of two transient species following 400 nm excitation of 2TP dissolved in acetonitrile. The first transient species forms within the instrument response time (70 ps) and decays within 6 ns. The second transient species forms on a timescale of ∼400 ps and decays on a 15 ns timescale. Time-dependent density functional theory is used to identify the first and second transient species as the lowest-lying triplet states of 2TP and 2MP, respectively. This study demonstrates transient S K-edge XA spectroscopy as a sensitive and viable probe of time-evolving charge dynamics near sulfur sites in small molecules with future applications towards studying complex biological and material systems.

Poly[[diaqua-bis-(μ(3)-isonicotinato-κN:O:O')bis-(μ(2)-isonicotinato-κN:O)gadolinium(III)disiliver(I)] nitrate monohydrate]

In the title compound, {[Ag(2)Gd(C(6)H(4)NO(2))(4)(H(2)O)(2)]NO(3)·H(2)O}(n), the Gd(III) ion is coordinated by eight O atoms from six isonicotinate ligands and two water mol-ecules in a distorted square anti-prismatic geometry. Two Ag(I) ions are each bonded to two N atoms from two isonicotinate ligands in a linear or bow-like fashion [N-Ag-N angles = 178.6 (2) and 147.1 (2)°]. These metal ions are connected by the isonicotin-ate ligands into a layer parallel to (010). O-H⋯O hydrogen bonds donated by the coordinated and uncoordinated water mol-ecules and intra-layer π-π stacking inter-actions between the pyridine rings [centroid-centroid distances = 3.551 (4) and 3.555 (4) Å] are observed. The layers inter-act with each other by inter-layer Ag⋯O(aqua) contacts [2.731 (4) Å] and π-π stacking inter-actions between the pyridine rings [centroid-centroid distances = 3.466 (3) and 3.516 (3) Å], resulting in the formation of a three-dimensional supra-molecular structure.