Polystyrene microplastic particles induce endothelial activation.

Due to its increasing production, durability and multiple applications, plastic is a material we encounter every day. Small plastic particles from the µm to the mm range are classified as microplastics and produced for cosmetic and medical products, but are also a result of natural erosion and decomposition of macroplastics. Although being omnipresent in our environment and already detected in various organisms, less is known about the effects of microplastics on humans in general, or on vascular biology in particular. Here we investigated the effects of carboxylated polystyrene microplastic particles (PS, 1 µm) on murine endothelial and immune cells, which are both crucially involved in vascular inflammation, using in vitro and in vivo approaches. In vitro, PS induced adhesion molecule expression in endothelial cells with subsequent adhesion of leukocytes both under static and flow conditions. In monocytic cells, PS enhanced pro-inflammatory cytokine expression and release. Accordingly, administering mice with PS led to enhanced aortic expression of cytokines and adhesion molecules. Furthermore, we identified neutrophils as the PS-clearing blood leukocyte population. The findings from this study for the first time indicate polystyrene microplastic as a new environmental risk factor for endothelial inflammation.

Solvent-Induced Bond-Bending Isomerism in Hexaphenyl Carbodiphosphorane: Decisive Dispersion Interactions in the Solid State.

Previous reports in the literature describe that the crystallization of hexaphenyl carbodiphosphorane (CDPPh) from a variety of solvents gives a "bent" geometry for the P-C-P moiety as the solid-state molecular structure. However, a linear structure is observed when CDPPh is crystallized from benzene. Here, we report detailed spectroscopic and theoretical studies on the linear and bent structures. X-ray powder diffraction examinations show a phase transition of linear CDPPh upon the loss of co-crystallized benzene molecules, which is accompanied by the bending of the P-C-P unit. Studies on the linear and bent structures (i.e., X-ray powder diffraction, solid-state NMR, UV-vis spectroscopy, and IR spectroscopy) show significant differences in their properties. Investigations of the solid-state structures with density functional theory-based methods (PBE-D3) point toward subtle dispersion effects being responsible for this solvent-induced bond-bending isomerism in CDPPh.

Double donation in trigonal planar iron-carbodiphosphorane complexes - a concise study on their spectroscopic and electronic properties.

We present the syntheses of trigonal planar coordinated Fe(ii) carbodiphosphorane (CDPR) complexes, starting from iron(ii)-bis(trimethylsilylamide) [Fe{N(SiMe3)2}2] and hexaphenyl-(CDPPh) and sym-dimethyltetraphenyl-carbodiphosphoranes (CDPMe), respectively. Both complexes [CDPPh-Fe{N(SiMe3)2}2] (1) and [CDPMe-Fe{N(SiMe3)2}2] (2) were examined in solution and in the solid state. 1 shows a dissociation equilibrium in solution which we monitored by variable temperature 1H-NMR spectroscopy. Magnetic measurements of 1 and 2 yielded a high spin configuration (S = 2) for both complexes. Quantum chemical calculations were performed to analyze the bonding situation in compound 1.

Hexaphenyl carbodiphosphorane adducts of heavier group 15 element trichlorides: syntheses, properties and reactivities.

Herein, we present a series of hexaphenyl carbodiphosphorane (CDPPh) adducts of heavier group 15 trichlorides ECl3 (E = P-Bi). The reaction with PCl3 yields the known salt [CDPPh-PCl2][Cl] ([1][Cl]), the heavier element trichlorides ECl3 (E = Sb (4), Bi (5)) give the neutral adducts CDPPh-ECl3 which were characterised crystallographically and spectroscopically. The reaction of CDPPh with AsCl3 does not yield CDPPh-AsCl3 (2), but in the presence of GaCl3 the corresponding salt [CDPPh-AsCl2][GaCl4] ([3][GaCl4]) is formed. DFT (density functional theory) calculations were carried out to examine the molecular frontier orbitals in 1+-5. Additional reactivity studies revealed an intramolecular electrophilic aromatic substitution (SEAr) in 1+, which represents an excellent starting point for further selective C-P bond formation reactions.

A new anthraquinoid ligand for the iron-catalyzed hydrosilylation of carbonyl compounds at room temperature: new insights and kinetics.

The reaction of 1-((2-(pyridin-2-yl)ethyl)amino)anthraquinone with either Fe(HMDS)2 or Li(HMDS)/FeCl2 allowed the preparation of a new anthraquinoid-based iron(ii) complex active in the hydrosilylations of carbonyls. The new complex Fe(2)2 was characterized by single-crystal X-ray diffraction, infrared spectroscopy, NMR, and high resolution mass spectrometry (electrospray ionization). Superconducting quantum interference device (SQUID) magnetometry established no spin crossover behavior with an S = 2 state at room temperature. This complex was determined to be an effective catalyst for the hydrosilylation of aldehydes and ketones, exhibiting turnover frequencies of up to 63 min-1 with a broad functional group tolerance by just using 0.25 mol% of the catalyst at room temperature, and even under solvent-free conditions. The aldehyde hydrosilylation makes it one of the most efficient first-row transition metal catalysts for this transformation. Kinetic studies have proven first-order dependences with respect to acetophenone and Ph2SiH2 and a fractional order in the case of the catalyst.

Proton Affinities of Cationic Carbone Adducts [AC(PPh3 )2 ](+) (A=Halogen, Hydrogen, Methyl) and Unusual Electronic Structures of the Cations and Dications [AC(H)(PPh3 )2 ](2.).

This work reports the syntheses and the first crystal structures of the cationic carbone adducts [FC(PPh3 )2 ](+) and [BrC(PPh3 )2 ](+) and the protonated dication [FC(H)(PPh3 )2 ](2+) , which are derived from the carbone C(PPh3 )2 . Quantum chemical calculations and bonding analyses were carried out for the series of cations [AC(PPh3 )2 ](+) and dications [AC(H)(PPh3 )2 ](2+) , where A=H, Me, F, Cl, Br, I. The bonding analysis suggests that the cations are best described as phosphane complexes L→(CA)(+) ←L (L=PPh3 ), which are related to the neutral borylene adducts L→(BA)←L (L=cyclic carbene; A=H, aryl) that were recently isolated. The carbone adducts [AC(PPh3 )2 ](+) possess a π electron lone pair at carbon and they can easily be protonated to the dications [AC(H)(PPh3 )2 ](2+) . The calculations of the dications indicate that the molecules are best represented as complexes L→(CHA)(2+) ←L (L=PPh3 ) where a carbene dication is stabilized by the ligands. The central carbon atom in the cations and even in the dications carries a negative partial charge, which is larger than the negative charge at fluorine. There is also the peculiar situation in which the carbon-fluorine bonds in [FC(PPh3 )2 ](+) and [FC(H)(PPh3 )2 ](2+) exhibit the expected polarity with the negative end at fluorine, but the carbon atom has a larger negative charge than fluorine. Given the similarity of carbodiphosphorane C(PPh3 )2 and carbodicarbene C(NHC)2 , we expect that analogous compounds [AC(NHC)2 ](+) and [AC(H)(NHC)2 ](2+) with similar features as [AC(PPh3 )2 ](+) and [AC(H)(PPh3 )2 ](2+) can be isolated.

On the solution behaviour of benzyllithium·(-)-sparteine adducts and related lithium organyls--a case study on applying 7Li,15N{1H} HMQC and further NMR methods, including some investigation into asymmetric synthesis.

2D (7)Li,(15)N heteronuclear shift correlation through scalar coupling has successfully been applied to several lithium organyls consisting of polydentate N ligands such as N,N,N',N'-tetramethylethylenediamine (tmeda), N,N,N',N',N''-pentamethyldiethylentriamine (pmdta) and (-)-sparteine. Structural insights on the conformation of benzyllithium·pmdta (5) in a toluene solution and the strength of ion pairing in combination with PGSE NMR measurements, (1)H,(1)H-NOESY and (1)H,(7)Li-HOESY experiments are presented. By studying in detail the formation of 5 in solution, a transient species has been observed for the first time and assigned to a pre-complex of nBuLi and pmdta. In addition, the solution behaviour of the complex formed between benzyllithium and (-)-sparteine (8) has been studied by PGSE and multinuclear NMR spectroscopy. The straightforward synthesis and first applications in asymmetric lithiations are also reported, which show that the new system benzyllithium·(-)-sparteine (8) provide poorer enantioselective induction than the classical nBuLi·(-)-sparteine (6). The results were supported by deprotonation experiments confirming that the formation of 8 relies on two relevant factors, namely temperature and lithiating reagent. The existence of 8 may thus interfere with the asymmetric induction when the system nBuLi· (-)-sparteine is used in the enantioselective deprotonations of N-Boc-N-(p-methoxyphenyl)-benzylamine conducted in toluene.

Synthesis of a GaN cage compound with a hydrazinetetraide fragment, [N-N]4-, stabilised by six gallium atoms.

Thermolysis of the bicyclic gallium hydrazide [(GaMe(2))(4)(NH-NMe)(NH-NHMe)(2)] (1) yielded the unique cage compound [(GaMe)(4)(GaMe(2))(4)(N(2))(NH-NMe)(4)] (2). Compound 2 contains a remarkable hydrazinetetraide moiety, [N-N](4-), as the central structural motif which is stabilised by coordination to six gallium atoms.

Syntheses, structures and electronic properties of zwitterionic iron(II) and cobalt(II) complexes featuring ambidentate tris(pyrazolyl)methanide ligands.

By deprotonation of the corresponding tris(pyrazolyl)methane ((Me)Tpm) precursor complexes [M((Me)Tpm)(2)][(OTf)(2)] (1 and 2), the zwitterionic tris(pyrazolyl)methanide iron(II) (3) and cobalt(II) (4) "sandwich" complexes of the general formula [M((Me)Tpmd)(2)] are easily accessible. The structurally characterised complexes 3 and 4 are the first such homoleptic 3d transition metal species to feature two "naked", outward pointing pyramidal carbanions. Density functional theory calculations show metal-centred HOMOs and LUMOs with the destabilised carbanion orbitals in the energy region of the filled transition-metal-centred frontier orbitals. The electronic structures of these complexes have been investigated in detail by various spectroscopic techniques such as NMR, EPR, SQUID, Mössbauer, etc. Both complexes adopt a high-spin (HS) configuration at room temperature in solution and in the solid state. A thermally induced high-spin to low-spin (HS-LS) transition is observed for the iron(II) complex 3. The HS-LS transition temperature of 3 in solution differs from that in the solid state, which in turn strongly depends on the amount of solvent molecules in the crystal lattice. Electrochemical studies on the corresponding cobalt(II) complex 4 provide evidence for a HS-Co(II) <==> LS-Co(III) transition upon oxidation, which was confirmed by preliminary synthetic oxidation reactions. Overall, it can be concluded that the related kappa(3)N-donor ligands tris(pyrazolyl)hydroborates (Tp(R)) and (R)Tpmd ligands have similar bonding properties and that the metal cations experience more or less the same ligand environment.

Multidentate ligand systems featuring dual functionality.

Multifunctional ligands with podand topology provide intrinsically well-defined coordination geometries. Several subgroups of multidentate ligand systems comprising dual functionality have been developed so far. Recent advances made in this research area reflect its topicality. Work on metal complexes of ambiphilic ligands consisting of Lewis-acidic Group 13 element bridgehead atoms and additional donor functionalities is in the current focus of interest. The intrinsic topology of tetradentate ligands may introduce a fascinating reactivity and interesting electronic properties to the metal complexes. Janus-head type ligands are very promising candidates for the preparation of multimetallic complexes.

Selection of a pentameric host in the host-guest complexes [[[[P(mu-NtBu)]2(mu-NH)]5].I]-[Li(thf)4]+ and [[[P(mu-NtBu)]2(mu-NH)]5].HBr.THF.

The structures of the host-guest complexes [[[[P(mu-NtBu)]2(mu-NH)]5]I]-.[Li(thf)4]+ [2.I[Li(thf)4]] and [[[P(mu-NtBu)]2(mu-NH)]5].HBr.THF (2.HBr.THF) show that increased distortion of the framework of the pentameric macrocycle [[[P(mu-NtBu)]2(mu-NH)]5] (2) occurs with the larger halide ions. Theoretical studies show that the thermodynamic stabilities of the model host-guest anions [2.X]- (X=Cl, Br, I) are in the order Cl- approximately Br->I-, that is, the reverse of the templating trend observed experimentally. These studies support the view that the selection of the pentamer 2 over the tetramer [[[P(mu-NtBu)]2(mu-NH)]4] (1) is kinetically controlled, a conclusion which is also consistent with the previous observation that the frameworks of 1 and 2 are not in dynamic equilibrium with each other.

The formation of dimeric phosph(III)azane macrocycles [[P(mu-NtBu)]2.LL]2 [LL = organic spacer].

The dimeric macrocycles [[P(mu-NtBu)]2.LL]2 [LL = OCH2C(Me)2CH2O (1), 2,6-(NH)2C5H3N (2), 1,2-(NH)2C6H4(3)] have been obtained by the reactions of the appropriate diols and diamines (LLH2) with the dimeric phosph(III)azane [ClP(mu-NtBu)]2. Under different conditions the reaction of 1,2-(NH2)2C6H4 with [ClP(mu-NtBu)]2 gives the monomer [[P(mu-NtBu)]2.[1,2-(NH)2C6H4]] (4) (instead of the dimer 3). Contrary to the literature, the results illustrate that the formation of dimeric macrocycles is common in these reactions and dependent among other factors on the steric demands and length of the organic spacer (LL) as well as the reaction conditions.