K9CeP4S16, a new thio­phosphate of cerium with discrete [Ce(PS4)4]9− anions

The structure of nona­potassium cerium tetra­phos­phorus hexa­deca­sulfide, a zero‐dimensional material isostructural with Rb₉CeP₄Se₁₆, is reported.     

Combinatorial Approach to Chiral Tris‐ligated Carbophilic Platinum Complexes: Application to Asymmetric Catalysis

A straightforward methodology for the synthesis of libraries of chiral tris‐ligated cationic platinum complexes and their in situ evaluation as asymmetric carbophilic catalysts in a model domino hydroarylation/cyclization reaction of a 1,6‐enyne was developed. A catalyst‐generation process based on a combination of a monodentate and a bidentate phosphorus ligand allowed the formation of 108 chiral complexes. One‐pot screening of the stereoinduction obtained with this library in a test domino addition/cyclization reaction validated this approach and stressed the key role played by the monodentate ligand partner in obtaining high enantioselectivities. In the case of two challenging substrate/nucleophile combinations, the combinatorial approach resulted in a significant gain in enantioselectivity.     

Competitive reactions of organophosphorus radicals on coke surfaces

The efficacy of organophosphorus radicals as anticoking agents was subjected to a computational study in which a representative set of radicals derived from industrially relevant organophosphorus additives was used to explore competitive reaction pathways on the graphene-like coke surface formed during thermal cracking. The aim was to investigate the nature of the competing reactions of different organophosphorus radicals on coke surfaces, and elucidate their mode of attack and inhibiting effect on the forming coke layer by use of contemporary computational methods. Density functional calculations on benzene and a larger polyaromatic hydrocarbon, namely, ovalene, showed that organophosphorus radicals have a high propensity to add to the periphery of the coke surface, inhibiting methyl radical induced hydrogen abstraction, which is known to be a key step in coke growth. Low addition barriers reported for a phosphatidyl radical suggest competitive aptitude against coke formation. Moreover, organophosphorus additives bearing aromatic substituents, which were shown to interact with the coke surface through dispersive π-π stacking interactions, are suggested to play a nontrivial role in hindering further stacking among coke surfaces. This may be the underlying rationale behind experimental observation of softer coke in the presence of organophosphorus radicals. The ultimate goal is to provide information that will be useful in building single-event microkinetic models. This study presents pertinent information on potential reactions that could be taken up in these models.     

A Switchable Domino Process for the Construction of Novel CO2‐Sourced Sulfur‐Containing Building Blocks and Polymers

α‐Alkylidene cyclic carbonates (αCCs) recently emerged as attractive CO₂‐sourced synthons for the construction of complex organic molecules. Herein, we report the transformation of αCCs into novel families of sulfur‐containing compounds by organocatalyzed chemoselective addition of thiols, following a domino process that is switched on/off depending on the desired product. The process is extremely fast and versatile in substrate scope, provides selectively linear thiocarbonates or elusive tetrasubstituted ethylene carbonates with high yields following a 100 % atom economy reaction, and valorizes CO₂ as a renewable feedstock. It is also exploited to produce a large diversity of unprecedented functional polymers. It constitutes a robust platform for the design of new sulfur‐containing organic synthons and important families of polymers.     

Overview of N-Rich Antennae Investigated in Lanthanide-Based Temperature Sensing

The market share of noncontact temperature sensors is expending due to fast technological and medical evolutions. In the wide variety of noncontact sensors, lanthanide-based temperature sensors stand out. They benefit from high photostability, relatively long decay times and high quantum yields. To circumvent their low molar light absorption, the incorporation of a light-harvesting antenna is required. This Review provides an overview of the nitrogen-rich antennae in lanthanide-based temperature sensors, emitting in the visible light spectrum, and discusses their temperature sensor ability. The N-rich ligands are incorporated in many different platforms. The investigation of different antennae is required to develop temperature sensors with diverse optical properties and to create a diverse offer for the multiple application fields. Molecular probes, consisting of small molecules, are first discussed. Furthermore, the thermometer properties of ratiometric temperature sensors, based on di- and polynuclear complexes, metal–organic frameworks, periodic mesoporous organosilicas and porous organic polymers, are summarized. The antenna mainly determines the application potential of the ratiometric thermometer. It can be observed that molecular probes are operational in the broad physiological range, metal–organic frameworks are generally very useful in the cryogenic region, periodic mesoporous organosilica show temperature dependency in the physiological range, and porous organic polymers are operative in the cryogenic-to-medium temperature range.     

Brønsted Acid Catalyzed Tandem Defunctionalization of Biorenewable Ferulic acid and Derivates into Bio‐Catechol

An efficient conversion of biorenewable ferulic acid into bio‐catechol has been developed. The transformation comprises two consecutive defunctionalizations of the substrate, that is, C?O (demethylation) and C?C (de‐2‐carboxyvinylation) bond cleavage, occurring in one step. The process only requires heating of ferulic acid with HCl (or H₂SO₄) as catalyst in pressurized hot water (250 °C, 50 bar N₂). The versatility is shown on a variety of other (biorenewable) substrates yielding up to 84 % di‐ (catechol, resorcinol, hydroquinone) and trihydroxybenzenes (pyrogallol, hydroxyquinol), in most cases just requiring simple extraction as work‐up.     

Bis-β-cyclodextrinyl- and bis-cellobiosyl-diazacrowns: synthesis and molecular complexation behaviors toward Busulfan anticancer agent and two basic aminoacids

The one-step synthesis of two C₂-symmetric receptors including two β-cyclodextrin cores or two disaccharidyl units connected by urea linkers to a diazacrown ether organizing platform is reported. The X-ray structure of the peracetylated bis-ureidocellobiosyl podand could be determined. These molecular systems, long thought to be potent selective carriers for chiral/achiral organic guests at the supramolecular level, were found to be efficient complexing tools toward the Busulfan anticancer agent but also toward l-arginine and l-lysine basic aminoacids.     

Degree functions and projectively full ideals in 2-dimensional rational singularities that can be desingularized by blowing up the unique maximal ideal

Let (R,m) be a 2-dimensional rational singularity with algebraically closed residue field and for which the associated graded ring is an integrally closed domain. According to Göhner, (R,m) satisfies condition (N): given a prime divisor v, there exists a unique complete m-primary ideal A_v in R with T(A_v)={v} and such that any complete m-primary ideal with unique Rees valuation v, is a power of A_v. We use the theory of degree functions developed by Rees and Sharp as well as some results about regular local rings, to investigate the degree coefficients d(A_v,v). As an immediate corollary, we find that for a simple complete m₁-primary ideal I₁ in an immediate quadratic transform (R₁,m₁) of (R,m); the inverse transform of I₁ in R is projectively full.     

Conclusive evidence for a retention-retention pathway for the molybdenum-catalyzed asymmetric alkylation

Enantiomerically enriched, deuterated branched carbonates (Z)-(S)-PhCH(O2COMe)-CH=CHD (1a), (Z)-(R)-PhCH(O2COMe)CH=CHD (2a), and linear carbonate (E)-(S)-PhCH=CHCHD(O2COMe) (12) were employed as probes in the Mo-catalyzed asymmetric allylic alkylation with sodium dimethyl malonate, catalyzed by ligand complex 10 derived from the mixed benzamide/picolinamide of (S,S)-trans-diaminocyclohexane and (norbornadiene)Mo(CO)4. X-ray crystallography, along with solution NMR structural analysis of the pi-allyl intermediate and competition experiments, conclusively established the reaction proceeded via a retention-retention pathway. This mechanism contrasts with that defined for Pd-catalyzed allylic alkylations, which proceed via an inversion-inversion pathway.