Stabilization versus competing de-metalation, trans-metalation and (cyclo)-dehydrogenation of Pd porphyrins at a copper surface.

Metal-porphyrins are studied intensively due their potential applications, deriving from the variety of electronic and chemical properties, tunable by selecting metal centers and functional groups. Metalation, de- and trans-metalation processes are fundamental in this sense to investigate both the synthesis and the stability of these molecular building blocks. More specifically, Pd coordination in tetrapyrroles revealed to be potentially interesting in the fields of cancer therapy, drug delivery and light harvesting. Thus, we focused on the stability of palladium tetraphenyl porphyrins (PdTPPs) on a copper surface by means of combined spectroscopy and microscopy approaches. We find that PdTPPs undergo coverage-dependent trans-metalation accompanied by steric rearrangements already at room temperature, and fully trans-metalate to CuTPPs upon mild annealing. Side reactions such as (cyclo)-dehydrogenation and structural reorganization affect the molecular layer, with Pd-Cu alloying and segregation occurring at higher temperature. Instead, oxygen passivation of the Cu support prevents the metal-involving reactions, thus preserving the layer and increasing the chemical and temperature stability of the Pd porphyrins.

FlexPES: a versatile soft X-ray beamline at MAX†IV Laboratory.

FlexPES is a soft X-ray beamline on the 1.5 GeV storage ring at MAX IV Laboratory, Sweden, providing horizontally polarized radiation in the 40-1500 eV photon energy range and specializing in high-resolution photoelectron spectroscopy, fast X-ray absorption spectroscopy and electron-ion/ion-ion coincidence techniques. The beamline is split into two branches currently serving three endstations, with a possibility of adding a fourth station at a free port. The refocusing optics provides two focal points on each branch, and enables either focused or defocused beam on the sample. The endstation EA01 at branch A (Surface and Materials Science) is dedicated to surface- and materials-science experiments on solid samples at ultra-high vacuum. It is well suited not only to all flavours of photoelectron spectroscopy but also to fast (down to sub-minute) high-resolution X-ray absorption measurements with various detectors. Branch B (Low-Density Matter Science) has the possibility to study gas-phase/liquid samples at elevated pressures. The first endstation of this branch, EB01, is a mobile setup for various ion-ion and electron-ion coincidence techniques. It houses a versatile reaction microscope, which can be used for experiments during single-bunch or multi-bunch delivery. The second endstation, EB02, is based on a rotatable chamber with an electron spectrometer for photoelectron spectroscopy studies on primarily volatile targets, and a number of peripheral setups for sample delivery, such as molecular/cluster beams, metal/semiconductor nanoparticle beams and liquid jets. This station can also be used for non-UHV photoemission studies on solid samples. In this paper, the optical layout and the present performance of the beamline and all its endstations are reported.

Order, disorder, and metalation of tetraphenylporphyrin (2H-TPP) on Au(111).

A thermally induced order-disorder transition of tetraphenylporphyrin (2H-TPP) on Au(111) is characterised by scanning probe microscopy and X-ray photoelectron spectroscopy-based techniques. We observed that a transition from an ordered close-packed phase to a disordered diffuse phase is correlated with an on-surface cyclodehydrogenation reaction, and that additional heating of this diffuse phase gives rise to a single distinct nitrogen environment indicative of the formation of a Au-TPP species.

Two polymorphic forms of the oxathiin systemic fungicide active carboxine.

Two polymorphic crystal forms of the title compound, C12H13NO2S (systematic name: 6-methyl-N-phenyl-2,3-di-hydro-1,4-oxathiine-5-carboxamide), were isolated from a truncated, (12 solvent), polymorph screen on pure lyophillized material. Crystals of form 1 were obtained from all solvents included in the screen with the exception of methanol. As isolated from aceto-nitrile the crystals are triclinic, space group P with Z' = 2. Crystals of form 2, which were isolated from methanol only are monoclinic, space group I2/a with Z' = 1. The crystal packing in both structures is dominated by the formation of infinite -NH⋯O hydrogen-bonded chains through the carboxamide core.