Isomerisation of allylic alcohols to saturated ketones can be efficiently catalysed by a heterogeneous molecular system resulting from Ir III Cp* anchoring to a covalent triazine framework. The obtained catalysts are active, selective, and fully recyclable.Transfer hydrogenation (TH) reaction -the addition of hydrogen to an unsaturated group of an organic molecule from a source other than H 2 -has been gaining a lot of attention as it is an appealing alternative to direct hydrogenation.1 The reasoning behind it is the elimination of pressurised hydrogen and high pressure equipment use. Besides, a conventional hydrogenation catalyst is rarely selective -any present unsaturated or oxidised functional group is exposed to reduction, resulting in, most of the time, a fully hydrogenated product or a mixture of products. Exceptions for highly chemoselective hydrogenation catalysts exist, such as noble metal nanoparticles supported on metal oxides or encapsulated inside metal-organic frameworks. 2-4In contrast with conventional hydrogenation, TH allows the reaction to be performed selectively, aiming for a specific unsaturated bond and leaving the rest of the original molecule intact.A conventional TH catalyst is a transition metal complex; among different metals, iridium is the most active one. Ir complexes involving a N-heterocycle carbene ligand, Covalent Triazine Frameworks (CTFs), a subclass of POFs, are highly porous and stable solids made by trimerisation of aromatic nitriles. 58,59 CTFs are rich in nitrogen functionalities, and their distribution can be varied by using different building blocks. Starting from a pyridine containing building unit, quasibipyridine moieties become available in the final material. Bipyridine is a widely-applied ligand in organometallic chemistry; its presence within a framework enables anchoring of a transition-metal complex. Following this approach, a number of molecular heterogeneous catalysts were developed for a range of different catalytic reactions by several research groups. 59-67Recently, we developed a CTF based catalyst which is highly active in the reversible formic acid (FA) dehydrogenation 4166 | CrystEngComm, 2017, 19, 4166-4170 This journal is

The information that can be obtained solely from the elemental analysis of soils, soil extracts and plant tissues by analytical atomic spectroscopy is of rather limited value as far as understanding the complex mechanisms of plant growth is concerned. As West (764) has pointed out, although the results of routine elemental analysis are invaluable for soil fertility assessment and related purposes, non-atomic spectrometric techniques now have perhaps a more vital role to play because of their importance in speciation studies. Thus the past year has largely been a further period of consolidation, with minor improvements to established procedures of atomic spectroscopy. One area which has however attracted substantial attention is that of sample preparation techniques. There has also been a slow but steady increase in the acceptance of much-improved commercially available ETA systems for those trace elements for which the improved detectability attainable may be deemed essential. Sample PreparationThe most time-consuming stage in the analysis of soils or plants by the majority of atomic spectroscopic techniques i s undoubtedly that of sample preparation. Moauro et al. (210) pointed out that the primary advantage of NAA over AAS for plant tissue analysis lies in the fact that sample dissolution i s unnecessary, Some attempts have been made to find new dissolution techniques that are faster and/or safer. Existing procedures have been critically compared. Scott and Thomas (922) compared three dissolution techniques for soils, Although all three gave reproducible results, they found that a Na,CO, fusion procedure gave lower results for Cd, Cu and Pb (particularly for soils with a high organic matter content) than two acid digestion techniques. One of these, sequential digestion with HF and HClO,, appears to be distinctly dangerous because of the possibility of being left with unattacked organic matter and concentrated HClO,. The other, based on HNO, /H,SO, /MClO, sounds more useful, particularly if the pump and air-bleed fume removal system described are used. Yamasaki (921) compared fusion of soils with 10 : 1 Na,CO, : H,BO, with sequential digestion with HNO,/HClO, and HF/HClO,. He found both to be apparently satisfactory for standard rock samples, but his study did not include any of the more volatile heavy trace metals. Ritter et al. (1092) compared five sample preparation techniques for soils and sewage sludges prior to the AAS determination of Cd, Cu, Ni, Pb and Zn. These included ignition at 550 "C and HCI extraction, HNO3/HC1O, digestion, extraction by shaking with 6M HNO, for 6 h, HCl/HNO, extraction, and ignition at 550 "C following by HCl/HF digestion. No losses from dry ashing were observed, but spattering and contamination problems were encountered in wet ashing procedures.The preliminary results of another comparison of wet and dry ashing procedures, but for marine plant samples, have also been reported (1583). Significant losses of Pb were observed, even at 350 "C. Wahdat and Shamsipoor (491) have descr...