Control of Λ- and Δ-Isomerization of the Atrane Cages in Group XIV Metallatranes by Chiral Axial Substituents.

The syntheses of the novel stannatranes N(CH2CMe2O)3Sn-(1 S)-(-)-OC(O)C(OMe)(CF3)(C6H5), 1( S, Δ), and N(CH2CMe2O)3Sn-(1 R)-(+)-OC(O)C(OMe)(CF3)(C6H5), 2( R, Λ), and germatranes N(CH2CMe2O)3Ge-(1 S)-(-)-OC(O)C(OMe)(CF3)(C6H5), 3( S, Δ), and N(CH2CMe2O)3Ge-(1 R)-(+)-OC(O)C(OMe)(CF3)(C6H5), 4( R, Λ) (with 1, S, Δ-configured/2, R, Λ-configured and 3, S, Δ-configured/4, R, Λ-configured being pairs of enantiomers) are reported. The compounds were characterized by NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single crystal X-ray diffraction analysis. The epimerization via Λ â‡Œ Δ ring flip of the enantiomeric stannatrane pair 1( S, Δ)/2( R, Λ) was investigated by NMR experiments at variable temperatures and density functional theory (DFT) calculations.

18F-Radiolabeling and In Vivo Analysis of SiFA-Derivatized Polymeric Core-Shell Nanoparticles.

Nanoparticles represent the most widely studied drug delivery systems targeting cancer. Polymeric nanoparticles can be easily generated through a microemulsion polymerization. Herein, the synthesis, radiolabeling, and in vivo evaluation of nanoparticles (NPs) functionalized by an organosilicon fluoride acceptor (SiFA) are reported which can be radiolabeled without further chemical modifications. Four nanoparticles in the sub-100 nm range with distinct hydrodynamic diameters of 20 nm (NP1), 33 nm (NP2), 45 nm (NP3), and 72 nm (NP4), respectively, were synthesized under size-controlled conditions. The SiFA-labeling building block acted as an initiator for the polymerization of polymer P1. The nanoparticles were radiolabeled with fluorine-18 (18F) through simple isotopic exchange (IE) and analyzed in vivo in a murine mammary tumor model (EMT6). The facile 18F radiolabeling SiFA methodology, performed in ethanol under mild reaction conditions, gave radiochemical yields (RCYs) of 19-26% and specific activities (SA) of 0.2-0.3 GBq/mg. Based on preclinical PET analysis, the tumor uptake and clearance profiles were analyzed depending on particle size. The nanoparticle size of 33 nm showed the highest tumor accumulation of SUVmean 0.97 (= 4.4%ID/g) after 4 h p.i. through passive diffusion based on the Enhanced Permeability and Retention (EPR) effect. Overall, this approach exhibits a simple, robust, and reliable synthesis of 18F radiolabeled polymeric nanoparticles with a favorable in vivo evaluation profile. This approach represents a straightforward synthetically accessible alternative to produce radiolabeled nanoparticles without any further surface modification to attach a radioisotope.

Cis versus Trans: The Coordination Environment about the Tin(IV) Atom in Spirocyclic Amino Alcohol Derivatives.

The syntheses of amino alcohols MeN(CH2 CH2 CMe2 OH)2 (1), MeN(CMe2 CH2 OH)(CH2 CMe2 OH) (2), MeN(CH2 CH2 CH2 OH)(CH2 CMe2 OH) (3), MeN(CH2 CH2 CMe2 OH)(CH2 CMe2 OH) (4), MeN(CH2 CH2 CMe2 OH)(CH2 CH2 OH) (5), and MeN(CH2 CH2 OH) (CH2 CH2 CH2 OH) (6) as well as spirocyclic tin(IV) alkoxides spiro-[nBuN(CH2 CMe2 O)2 ]2 Sn (7), spiro-[MeN(CH2 CH2 CMe2 O)2 ]2 Sn (8), spiro-[para-FC6 H4 N (CH2 CMe2 O)2 ]2 Sn (9), spiro-[MeN(CMe2 CH2 O)(CH2 CMe2 O)]2 Sn (10), spiro-[MeN(CH2 CH2 CH2 O)(CH2 CMe2 O)]2 Sn (11), spiro-[MeN(CH2 CH2 CMe2 O)(CH2 CMe2 O)]2 Sn (12), spiro-[MeN(CH2 CH2 CMe2 O)(CH2 CH2 O)]2 Sn (13) and spiro-[MeN(CH2 CH2 O)(CH2 CH2 CH2 O)]2 Sn (14) are reported. The compounds were characterized by 1 H, 13 C (1-14) and 119 Sn (7-14) NMR and IR spectroscopy, EIMS and single-crystal XRD (2, 7-10 and 13, 14). Graph-set analyses were performed for compounds [(MeNH(CMe2 CH2 OH)(CH2 CMe2 OH)][HC(O)O] (2 a) and 2. The coordination environment about the tin(IV) centre of the spirocyclic compounds and their possible stereoisomers were analysed by DFT calculations (spiro-[MeN(CH2 CMe2 O)2 ]2 Sn, 8-10 and 13).

Hydrosilylation of RN=CH Imino-Substituted Pyridines without a Catalyst.

Treatment of the neutral pyridine-based ligands L1 -L3 , bearing either one or two RN=CH imine moieties {where L1 and L2 are N,N-chelating ligands 2-(RN=CH)C5 H4 N (R=Ph (L1 ) or R=2,4,6-Ph3 C6 H2 (L2 )) and L3 is the N,N,N-chelating ligand 2,6-(RN=CH)2 C5 H3 N (R=2,6-iPr2 C6 H3 )}, with HSiCl3 yielded N→Si-coordinated silicon(IV) amides 2-{Cl3 SiN(R)CH2 }C5 H4 N (1, R=Ph; 2, R=2,4,6-Ph3 C6 H2 ) and 2-{Cl3 SiN(R)CH2 }-6-(RN=CH)C5 H4 N (3, R=2,6-iPr2 C6 H3 ). The organosilicon amides 1-3 are the products of spontaneous hydrosilylation of the RN=CH imine moiety induced by N→Si coordination of the proposed N,N-chelated chlorosilanes L1 →SiHCl3 (1 a), L2 →SiHCl3 (2 a), and L3 →SiHCl3 (3 a). Furthermore, the reaction of L3 with an excess of HSiCl3 provided the intramolecularly coordinated chlorosilicon diamide cyclo-{(C5 H3 N)-1,3-(CH2 NR)2 }SiCl2 (4) (R=2,6-iPr2 C6 H3 ) as the product of spontaneous reduction of both RN=CH imine moieties. The compounds have been characterized by NMR spectroscopy (1-4) and single-crystal X-ray diffraction analysis (1, 3, and 4). The mechanism of the hydrosilylation of the second RN=CH imine moiety in 3 by an excess of SiHCl3 has also been studied. The experimental work is supplemented by DFT calculations.

Introducing Stereogenic Centers to Group XIV Metallatranes.

The syntheses of the novel amino alcohols NH(CH2CMe2OH)2(CMe2CH2OH) (1) and N(CH2CMe2OH)(CMe2CH2OH)(CH2CH2OH) (2) as well as the stannatranes N(CH2CMe2O)(CMe2CH2O)(CH2CH2O)SnX (3, X = Ot-Bu), N(CH2CMe2O)3SnOC(O)C9H13O2, 4, and germatranes N(CH2CMe2O)(CMe2CH2O)(CH2CH2O)GeX (5, X = OEt; 6, X = Br) are reported. The compounds were characterized by 1H, 13C (1-6), 119Sn (3, 4), and 15N (2, 3, 5) NMR and IR spectroscopy, electrospray ionization mass spectrometry, and single crystal X-ray diffraction analysis. Graphset analyses were performed for compounds 1 and 2. Detailed NMR spectroscopic studies including variable temperature 1H (3, 5, 6) and 119Sn (3, 4) DOSY experiments reveal the stannatrane 3 being involved in a monomer-dimer equilibrium. Both the stannatranes 3 and 4 as well as the germatranes 5 and 6 show Λ â‡Œ Δ isomerization of the atrane cages in solution.

Novel Stannatrane N(CH2CMe2O)2(CMe2CH2O)SnO-t-Bu and Related Oligonuclear Tin(IV) Oxoclusters. Two Isomers in One Crystal.

The syntheses of the alkanolamine N(CH2CMe2OH)2(CMe2CH2OH) (1), of the stannatrane N(CH2CMe2O)2(CMe2CH2O)SnO-t-Bu (2), and of the trinuclear tin oxocluster 3 consisting of the two isomers [(µ3-O)(O-t-Bu){Sn(OCH2CMe2)(OCMe2CH2)2N}3] (3a) and [(µ3-O)(µ3-O-t-Bu){Sn(OCH2CMe2)(OCMe2CH2)2N}3] (3b) as well as the isolation of a few crystals of the hexanuclear tin oxocluster [LSnOSn(OH)3LSnOH]2 [L = N(CH2CMe2O)2(CMe2CH2O)] (4) are reported. The compounds were characterized by 1H, 13C, 15N, and 119Sn (1-3) nuclear magnetic resonance and infrared spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analysis (1-4). A graph set analysis was performed for compound 1. The relative energies of 3a and 3b were estimated by density functional theory calculations that show that the energy differences are small.

N-Coordinated Tin(II) Trifluoromethanesulfonates and Their Reactions with Transition Metal Carbonyls.

The syntheses of the compounds [L(1)SnCl][M(CO)5(SnCl3)] (3, M = W; 4, M = Cr), [L(1)SnCl]OTf (5), [L(1)SnCl][W(CO)5(SnCl2OTf)] (6), [L(1)SnOTf][OTf] (7), and [L(2)Sn(OTf)2] (8) with L(1) = {2,6-[(CH3)C═N(C6H3-2,6-(i)Pr2)2]C5H3N} (DIMPY) and L(2) = {2-[(CH3)C═N(C6H3-2,6-(i)Pr2)]-6-(CH3O)}C5H3N) is reported. The compounds were characterized by elemental analyses, (1)H, (13)C, (19)F, and (119)Sn NMR spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analyses (3·1.5C7H8, 5·CH2Cl2, 7·C7H8, 8). For compounds 7 and 8, the experimental work is accompanied by density functional theory calculations.

Investigations on diffusion limitations of biocatalyzed reactions in amphiphilic polymer conetworks in organic solvents.

The use of enzymes as biocatalysts in organic media is an important issue in modern white biotechnology. However, their low activity and stability in those media often limits their full-scale application. Amphiphilic polymer conetworks (APCNs) have been shown to greatly activate entrapped enzymes in organic solvents. Since these nanostructured materials are not porous, the bioactivity of the conetworks is strongly limited by diffusion of substrate and product. The present manuscript describes two different APCNs as nanostructured microparticles, which showed greatly increased activities of entrapped enzymes compared to those of the already activating membranes and larger particles. We demonstrated this on the example of APCN particles based on PHEA-l-PDMS loaded with α-Chymotrypsin, which resulted in an up to 28,000-fold higher activity of the enzyme compared to the enzyme powder. Furthermore, lipase from Rhizomucor miehei entrapped in particles based on PHEA-l-PEtOx was tested in n-heptane, chloroform, and substrate. Specific activities in smaller particles were 10- to 100-fold higher in comparison to the native enzyme. The carrier activity of PHEA-l-PEtOx microparticles was tenfold higher with some 25-50-fold lower enzyme content compared to a commercial product.