Oligoorganogermanes: interplay between aryl and trimethylsilyl substituents

Derivatives of main group elements containing element–element bonds are characterized by unique properties due to -conjugation, which is an attractive subject for investigation. A novel series of digermanes, Ar3Ge-Ge(SiMe3)3, containing aryl (Ar = p-C6H4Me (1), p-C6H4F (2), C6F5 (3)) and trimethylsilyl substituents, was synthesized by the reaction of germyl potassium salt, [(Me3Si)3GeK*THF], with triarylchlorogermanes, Ar3GeCl. The optical and electronic properties of such substituted oligoorganogermanes were investigated spectroscopically by UV/vis absorption spectroscopy and theoretically by DFT calculations. The molecular structures of compounds 1 and 2 were studied by XRD analysis. Conjugation between all structural fragments (Ge-Ge, Ge-Si, Ge-Ar, where Ar is an electron-donating or withdrawing group) was found to affect the properties

Special section guest editorial: advances in terahertz biomedical science and applications

The Journal of Biomedical Optics (JBO) has published this special section of papers to capture the most recent advances in THz technology and innovative THz instruments and methods in biology and medicine. A few of the papers in this special section are dedicated to similar biomedical applications of novel optical tools from the neighboring infrared (IR) range. Two papers of the special section consider modern problems of oncodiagnosis. In the research article ‘Development of oral cancer tissue-mimicking phantom based on polyvinyl chloride plastisol and graphite for terahertz frequencies’, authors have introduced a new type of a water-free tissue-mimicking phantom for THz biophotonics. This phantom is based on graphite powders embedded into a polyvinyl chloride plastisol matrix. The effective THz optical properties of such a phantom can be managed in a wide range by changing its composition, thus allowing to mimic the THz optical properties of various biological tissues

Aryl oligogermanes as ligands for transition metal complexes

The ligand properties of a series of aryl oligogermanes R3Ge‐GeAr3, 3‐7 (Me3Ge‐GePh3 (3), Me3Ge‐Ge(pTol)3 (4), Ph3Ge‐GePh3 (5), (C6F5)3Ge‐GePh3 (6), Ph3Ge‐GeMe2GePh3 (7)), for the synthesis of transition metal carbonyl complexes such as R3Ge‐GeAr2(R’C6H4‐η6)M(CO)3 (M = Cr, 3a‐7a; M = Mo, 3b; M = W, 3c) were investigated. The target complexes were obtained in moderate yields using several different synthetic approaches. The physicochemical properties of these new derivatives were investigated by IR, UV/vis, NMR spectroscopy, electrochemistry and DFT calculations. The molecular structures of 3c, 4a and 5a were studied by single crystal X‐ray diffraction analysis. A comparative analysis of donor‐ and acceptor properties of aryl oligogermanes as ligands for transition metal carbonyl complexes is reported

Donor-acceptor molecular oligogermanes: Novel properties and structural aspects

The linear oligogermyl amide 2, Ph3GeGeMe2NMe2, was obtained by reacting Ph3GeLi with 1, Me2Ge(Cl)NMe2. The amide 2 was used for the synthesis of molecular oligogermanes 3, Ph3GeGeMe2Ge(C6F5)3, and 4, [Ph3GeGeMe2]2Ge(C6F5)2, containing electron donor (Me, Ph) and acceptor (C6F5) groups, by using a hydrogermolysis reaction in n-hexane. The molecular structures of 3 and 4 were studied by XRD. It was shown that in a crystal 3 forms wide channels, in which the solvated nonpolar n-hexane molecule is present. The NMR (1H, 13C and 19F), optical (UV/vis absorption, luminescence) and electrochemical (cyclic voltammetry) properties of both compounds were also studied. The impact of the substitution type by the electron withdrawing groups (at the terminal position, such as in 3, or within the compound, such as in 5), on the physical properties was also studied

Oligoorganogermanes: Interplay between Aryl and Trimethylsilyl Substituents

Derivatives of main group elements containing element–element bonds are characterized by unique properties due to σ-conjugation, which is an attractive subject for investigation. A novel series of digermanes, Ar3Ge-Ge(SiMe3)3, containing aryl (Ar = p-C6H4Me (1), p-C6H4F (2), C6F5 (3)) and trimethylsilyl substituents, was synthesized by the reaction of germyl potassium salt, [(Me3Si)3GeK*THF], with triarylchlorogermanes, Ar3GeCl. The optical and electronic properties of such substituted oligoorganogermanes were investigated spectroscopically by UV/vis absorption spectroscopy and theoretically by DFT calculations. The molecular structures of compounds 1 and 2 were studied by XRD analysis. Conjugation between all structural fragments (Ge-Ge, Ge-Si, Ge-Ar, where Ar is an electron-donating or withdrawing group) was found to affect the properties

Germanium Complexes with <i>O<u>N</u>O</i> Tridentate Ligands: O-H Bond Activation Control According to DFT Calculations

Polydentate ligands are used for thermodynamic stabilization of tetrylenes—low-valent derivatives of Group 14 elements (E = Si, Ge, Sn, Pb). This work shows by DFT calculations how the structure (the presence or absence of substituents) and type (alcoholic, Alk, or phenolic, Ar) of tridentate ligands 2,6-pyridinobis(1,2-ethanols) [AlkONOR]H2 and 2,6-pyridinobis(1,2-phenols) [ArONOR]H2 (R = H, Me) may affect the reactivity or stabilization of tetrylene, indicating the unprecedented behavior of Main Group elements. This enables the unique control of the type of the occurring reaction. We found that unhindered [ONOH]H2 ligands predominantly led to hypercoordinated bis-liganded {[ONOH]}2Ge complexes, where an E(+2) intermediate was inserted into the ArO-H bond with subsequent H2 evolution. In contrast, substituted [ONOMe]H2 ligands gave [ONOMe]Ge: germylenes, which may be regarded as kinetic stabilized products; their transformation into E(+4) species is also thermodynamically favorable. The latter reaction is more probable for phenolic [ArONO]H2 ligands than for alcoholic [AlkONO]H2. The thermodynamics and possible intermediates of the reactions were also investigated

Di-&#956;-oxido-bis({2,2&#8242;-[ethane-1,2-diylbis(nitrilomethanylylidene)]diphenolato}titanium(IV)) chloroform disolvate

In the title structure, [Ti2(C16H16N2O2)2O2]&#183;2CHCl3, the Ti atom is coordinated in a distorted octahedral geometry by the O,N,N&#8242;,O&#8242; donor set of the salalen ligand and by two &#956;2-oxide O atoms, which bridge two Ti(salalen) fragments into a centrosymmetric dimeric unit. In the central Ti2(&#956;2-O)2 fragment, the metal&#8211;oxygen distances are significantly different [1.7962&#8197;(19) and 1.9292&#8197;(19)&#8197;&#197;]. In the crystal, the chloroform molecule is anchored via an N&#8212;H...Cl and a bifurcated C&#8212;H...(O,O) hydrogen bond. Slipped &#960;&#8211;&#960; stacking [shortest C...C distance = 3.585&#8197;(4)&#8197;&#197;] and C&#8212;H...&#960; interactions contribute to the coherence of the structure

Crystal structure of (tert-butyldimethylsilyl)triphenylgermane, Ph3Ge-SiMe2(t-Bu)

In the title compound, Ph3Ge-SiMe2(t-Bu) or C24H30GeSi, the Si and Ge atoms both possess a tetrahedral coordination environment with C—E—C (E = Si, Ge) angles in the range 104.47 (5)–114.67 (5)°. The molecule adopts an eclipsed conformation, with three torsion angles less than 29.5°. In the crystal, neighbouring molecules are combined to dimers by six T-shaped C—H...π interactions, forming sixfold phenyl embraces (6PE)