Synthesis of the Bulky Phosphanide [P(SiPr)] and Its Stabilization of Low-Coordinate Group 12 Complexes.

Here, we report an improved synthesis of the bulky phosphanide anion [P(SiPr)] in synthetically useful yields and its complexation to group 12 metals. The ligand is obtained as the sodium salt NaP(SiPr) in a 42% isolated yield and a single step from red phosphorus and sodium. This is a significantly higher-yielding and safer preparation compared to the previously reported synthesis of this ligand, and we have thus applied to the synthesis of the two-coordinate complexes M[P(SiPr)] (M = Zn, Cd, Hg).

Mechanistic investigations of the Fe(ii) mediated synthesis of squaraines.

The scission and homologation of CO is a fundamental process in the Fischer-Tropsch reaction. However, given the heterogeneous nature of the catalyst and forcing reaction conditions, it is difficult to determine the intermediates of this reaction. Here we report detailed mechanistic insight into the scission/homologation of CO by two-coordinate iron terphenyl complexes.

Highly selective, reversible water activation by P,N-cooperativity in pyridyl-functionalized phosphinines.

Tetrapyridyl-functionalized phosphinines were prepared and structurally characterized. The donor-functionalized aromatic phosphorus heterocycles react highly selectively and even reversibly with water. Calculations reveal P,N-cooperativity for this process, with the flanking pyridyl groups serving to kinetically enhance the formal oxidative addition process of HO to the low-coordinate phosphorus atom H-bonding.

Advancing Brain Research through Surface-Enhanced Raman Spectroscopy (SERS): Current Applications and Future Prospects.

Surface-enhanced Raman spectroscopy (SERS) has recently emerged as a potent analytical technique with significant potential in the field of brain research. This review explores the applications and innovations of SERS in understanding the pathophysiological basis and diagnosis of brain disorders. SERS holds significant advantages over conventional Raman spectroscopy, particularly in terms of sensitivity and stability.

Uncovering potential diagnostic and pathophysiological roles of α-synuclein and DJ-1 in melanoma.

Background: Melanoma, the most lethal skin cancer type, occurs more frequently in Parkinson's disease (PD), and PD is more frequent in melanoma patients, suggesting disease mechanisms overlap. α-synuclein, a protein that accumulates in PD brain, and the oncogene DJ-1, which is associated with PD autosomal recessive forms, are both elevated in melanoma cells. Whether this indicates melanoma progression or constitutes a protective response remains unclear.

Phosphorus derivatives of mesoionic carbenes: synthesis and characterization of triazaphosphole-5-ylidene → BF adducts.

Trimethylsilyl-substituted triazaphospholes were synthesized by a [3+2] cycloaddition reaction between organic azides and (CH)Si-CP. In an attempt to isolate their -alkylated products, the formation of BF adducts of unprecedented triazaphosphol-5-ylidenes was found. The nature of the carbon-boron bond was investigated within the DFT framework, revealing a strong donation of electrons from the carbene carbon atom to the boron atom combined with weak back-bonding.

Homotropic Cooperativity in Iron-Catalyzed Alkyne Cyclotrimerizations.

Enhancing catalytic activity through synergic effects is a current challenge in homogeneous catalysis. In addition to the well-established metal-metal and metal-ligand cooperation, we showcase here an example of self- by the substrate in controlling the catalytic activity of the two-coordinate iron complex [Fe(2,6-XylCH)] (, Xyl = 2,6-MeCH). This behavior was observed for aryl acetylenes in their regioselective cyclotrimerization to 1,2,4-(aryl)-benzenes.

Phosphinine Selenide: Noncovalent Interactions with Organoiodines and Elemental Iodine, and Reactivity towards Potassium Cyanide.

Invited for this month's cover is the group of Prof. Dr. Christian Müller from Freie Universität Berlin, Germany.

Glycosylation spectral signatures for glioma grade discrimination using Raman spectroscopy.

Background: Gliomas are the most common brain tumours with the high-grade glioblastoma representing the most aggressive and lethal form. Currently, there is a lack of specific glioma biomarkers that would aid tumour subtyping and minimally invasive early diagnosis. Aberrant glycosylation is an important post-translational modification in cancer and is implicated in glioma progression.

The diagnostic and prognostic potential of the EGFR/MUC4/MMP9 axis in glioma patients.

Glioblastoma is the most aggressive form of brain cancer, presenting poor prognosis despite current advances in treatment. There is therefore an urgent need for novel biomarkers and therapeutic targets. Interactions between mucin 4 (MUC4) and the epidermal growth factor receptor (EGFR) are involved in carcinogenesis, and may lead to matrix metalloproteinase-9 (MMP9) overexpression, exacerbating cancer cell invasiveness.

Phospholenes from Phosphabenzenes by Selective Ring Contraction.

A 3-amino-functionalized phosphabenzene (phosphinine) has been synthesized and structurally characterized. The pyramidalized nitrogen atom of the dimethylamino substituent indicates only a weak interaction between the lone pair of the nitrogen atom and the aromatic phosphorus heterocycle, resulting in somewhat basic character. It turned out that the amino group can indeed be protonated by HCl.

Triple dehydrofluorination as a route to amidine-functionalized, aromatic phosphorus heterocycles.

An unexpected route to hitherto unknown amidine-functionalized phosphinines has been developed that is rapid and simple. Starting from primary amines and CF-substituted λ,σ-phosphinines, a cascade of dehydrofluorination reactions leads selectively to -amidinephosphinines. DFT calculations reveal that this unusual transformation can take place a series of nucleophilic attacks at the electrophilic, low-coordinate phosphorus atom.

Phosphinine Selenide: Noncovalent Interactions with Organoiodines and Elemental Iodine, and Reactivity towards Potassium Cyanide.

A co-crystalline adduct consisting of a phosphinine selenide and an organohalide was obtained by slow evaporation of the solvent from a mixture of 2,6-bis(trimethylsilyl)phosphinine selenide and 1,4-diiodotetrafluorobenzene (1,4-TFDIB). The crystallographic characterization of the product shows π-π stacking, F⋅⋅⋅H hydrogen bonding between 1,4-TFDIB and the phosphinine selenide, as well as F⋅⋅⋅F interactions between 1,4-TFDIB molecules. Moreover, the phosphorus heterocycle could be crystallized with diiodine to form a 1 : 1 adduct.

Reactivity of Sodium Pentaphospholide Na[cyclo-P ] towards C≡E (E=C, N, P) Triple Bonds.

A diglyme solution of Na[cyclo-P ] (1) reacts with alkynes and isolobal nitriles and phosphaalkynes to afford the otherwise elusive (aza)phospholide anions 2 a-c, 4 a,b, and 6. The reaction of Na[cyclo-P ] with alkynes and nitriles was studied by means of DFT methods, which suggested a concerted mechanism for the formation of 2 a and 4 b. The anions 2 a-c, 4 a,b, and 6 coordinate in an η -fashion towards Fe to give the sandwich (aza)phosphametallocenes 3 a-c, 5 a,b and 7 in moderate to good yields.

Borane Adducts of Aromatic Phosphorus Heterocycles: Synthesis, Crystallographic Characterization and Reactivity of a Phosphinine-B(C F ) Lewis Pair.

A phosphinine-borane adduct of a Me Si-functionalized phosphinine and the Lewis acid B(C F ) has been synthesized and characterized crystallographically for the first time. The reaction strongly depends on the nature of the substituents in the α-position of the phosphorus heterocycle. In contrast, the reaction of B H with various substituted phosphinines leads to an equilibrium between the starting materials and the phosphinine-borane adducts that is determined by the Lewis basicity of the phosphinine.

Photochemical C()-C() Bond Activation in Phosphaalkynes: A New Route to Reactive Terminal Cyaphido Complexes LM-C≡P.

The photochemical activation of the C()-C() bond in Pt(0)-η-aryl-phosphaalkyne complexes leads selectively to coordination compounds of the type LPt(aryl)(C≡P). The oxidative addition reaction is a novel, clean, and atom-economic route for the synthesis of reactive terminal Pt(II)-cyaphido complexes, which can undergo [3 + 2] cycloaddition reactions with organic azides, yielding the corresponding Pt(II)-triazaphospholato complexes. The C-C bond cleavage reaction is thermodynamically uphill.

One-step methylation of aromatic phosphorus heterocycles: synthesis and crystallographic characterization of a 1-methyl-phosphininium salt.

For the first time, the direct synthesis of 1-methyl-phosphininium salts has been achieved by reacting aromatic λ,σ-phosphinines with the readily available dimethyl chloronium salt [(CH)Cl][Al(OTeF)]. The remarkably high electrophilicity of the alkylation reagent in combination with the weakly coordinating pentafluoro-orthotelluratoaluminate anion offers excellent conditions for this one-step approach. Our simple and quantitative access to 1-methyl-phosphininium salts will pave the way to explore the chemistry of such reactive species in more detail.

Making Aromatic Phosphorus Heterocycles More Basic and Nucleophilic: Synthesis, Characterization and Reactivity of the First Phosphinine Selenide.

The synthesis and isolation of a phosphinine selenide was achieved for the first time by reacting red selenium with 2,6-bis(trimethylsilyl)phosphinine. The rather large coupling constant of J =883 Hz is in line with a P-Se bond of high s-character. The σ-electron donating Me Si-substituents significantly increase the energy of the phosphorus lone pair and hence its basicity, making the heterocycle considerably more basic and nucleophilic than the unsubstituted phosphinine C H P, as confirmed by the calculated gas phase basicities.

Room Temperature Iron-Catalyzed Transfer Hydrogenation and Regioselective Deuteration of Carbon-Carbon Double Bonds.

An iron catalyst has been developed for the transfer hydrogenation of carbon-carbon multiple bonds. Using a well-defined β-diketiminate iron(II) precatalyst, a sacrificial amine and a borane, even simple, unactivated alkenes such as 1-hexene undergo hydrogenation within 1 h at room temperature. Tuning the reagent stoichiometry allows for semi- and complete hydrogenation of terminal alkynes.

Iron Catalyzed Dehydrocoupling of Amine- and Phosphine-Boranes.

Catalytic dehydrocoupling methodologies, whereby dihydrogen is released from a substrate (or intermolecularly from two substrates) is a mild and efficient method to construct main group element-main group element bonds, the products of which can be used in advanced materials, and also for the development of hydrogen storage materials. With growing interest in the potential of compounds such as ammonia-borane to act as hydrogen storage materials which contain a high weight% of H, along with the current heightened interest in base metal catalyzed processes, this review covers recent developments in amine and phosphine dehydrocoupling catalyzed by iron complexes. The complexes employed, products formed and mechanistic proposals will be discussed.

A gene regulatory network model for floral transition of the shoot apex in maize and its dynamic modeling.

The transition from the vegetative to reproductive development is a critical event in the plant life cycle. The accurate prediction of flowering time in elite germplasm is important for decisions in maize breeding programs and best agronomic practices. The understanding of the genetic control of flowering time in maize has significantly advanced in the past decade.

QTL Controlling Masculinization of Ear Tips in a Maize (Zea mays L.) Intraspecific Cross.

Maize is unique among cereal grasses because of its monoecious flowering habit. Male flowers are normally restricted to the tassel that terminates the primary shoot, whereas female flowers occur as ears at the terminal nodes of lateral branches. We observed Ki14, a tropical maize inbred that produces an ear tipped by a staminate (male) spike under certain environmental conditions, such as long daylengths.

Genetic control of photoperiod sensitivity in maize revealed by joint multiple population analysis.

Variation in maize for response to photoperiod is related to geographical adaptation in the species. Maize possesses homologs of many genes identified as regulators of flowering time in other species, but their relation to the natural variation for photoperiod response in maize is unknown. Candidate gene sequences were mapped in four populations created by crossing two temperate inbred lines to two photoperiod-sensitive tropical inbreds.

Mapping resistance quantitative trait Loci for three foliar diseases in a maize recombinant inbred line population-evidence for multiple disease resistance?

Southern leaf blight (SLB), gray leaf spot (GLS), and northern leaf blight (NLB) are all important foliar diseases impacting maize production. The objectives of this study were to identify quantitative trait loci (QTL) for resistance to these diseases in a maize recombinant inbred line (RIL) population derived from a cross between maize lines Ki14 and B73, and to evaluate the evidence for the presence genes or loci conferring multiple disease resistance (MDR). Each disease was scored in multiple separate trials.