Dmitrii Yu. Antonov

Elaboration of a novel type of planar-chiral methylene bridged biphenols based on [2.2]paracyclophanes

Abstract A new class of chiral methylene bridged biphenols with planar chirality has been designed and elaborated. The synthetic approach is based on the use of 4-hydroxy-5-hydroxymethyl[2.2]paracyclophane 9 derived from either racemic or enantiomerically pure ( S ) - 4 - formyl-5-hydroxy[2.2.]paracyclophane (FHPC) by reduction with LiAlH 4 . The condensation of 9 with chiral racemic 4-hydroxy[2.2]paracyclophane 4 and achiral phenols, such as 2,5-dimethylphenol 10 and 2-isopropyl-5-methylphenol 11 , afforded the target bridged biphenols 6 , 12 and 13 , respectively. The preliminary results on the asymmetric addition of Et 2 Zn to benzaldehyde promoted by ( S,S ) - 6 are reported.

First stereoselective pinacol coupling in the [2.2]paracyclophane series

The planar chiral N-arylimines of [2.2]paracyclophane undergo stereoselective pinacol coupling under the action of the Zn/Cu couple in the presence of p-TosOH, thus forming N-aryl substituted 1,2-diamines. The stereoselective formation of the asymmetric centers is governed by the planar chiral [2.2]paracyclophanyl moiety.

Reactions of H2Os3(CO)10 with triallylboranes: formation of novel triosmium boron-containing olefin clusters

H2Os3(CO)10 (1) reacts with triallylborane B(CH2CHCH2)3 at 25 °C to form the cluster [Os3(CO)10(μ-η2:η2-trans-MeHCCH)2BC3H7] (2). Reaction of 1 with a mixture of triallylborane–trimethallylborane (1 : 3) gives a mixture of clusters 2, [Os3(CO)10(μ-η2:η2-Me2CCH)2BC3H7] (3) and {Os3(CO)10[μ-η2:η2-(trans-MeCHCH)(Me2CCH)]BC3H7} (4). The reaction results in the B–C bond cleavage and the isomerization of two allyl fragments into substituted vinyl groups coordinated to the osmium atoms in an η2-fashion, and reduction of the third fragment to a propyl group. The mechanism of the reaction is discussed based on isotope labelling and influence of the boron substituent ligand on the reaction path and product identity. Clusters 2, 3, 4 are characterized by spectroscopic means as well as by X-ray studies.

The substituted [2.2] paracyclophanes as versatile platform for a design of new optical materials

The series of novel unsymmetrical β--diketones substituted by functional groups with different donor-acceptor properties, as well as of their lanthanide complexes have been synthesized for the first time. The optical properties of these [2.2]paracyclophane-derived ligands and the lanthanide complexes were studied by UV-visible and luminescence spectroscopy. The energy of absorption maximum of these β--diketones correlates with donor-acceptor properties of functional groups and a size of the conjugated system. All β--diketonates synthesized exhibit broad emission spectra with red shifted maxima in comparison with isolated [2.2]paracyclophane moiety. The designed blue-emitting unsymmetrical β-diketones act as very efficient sensitizers of the Eu3+ emission with excitation wavelength up to 450 nm. Nonlinear optical properties have been studies for some β--diketones as well. Their average NLO susceptibility was found comparable with that of such well known NLO crystal as PNP.

NLO properties of formyl-methoxy derivatives of [2.2] paracyclophane containing the donor group in different positions

Formyl-methoxy derivatives of [2.2]paracyclophane (pCp) have been synthesized and studied by optical spectroscopy as well as the X-ray diffraction method. These molecules crystallize in acentric space groups. The efficiency of SHG ability of these compounds was measured by the powder technique at 1064 nm fundamental wavelength and average NLO susceptibility for some of them was found comparable with such well-known NLO crystal as NPP. The calculations of molecular and crystalline nonlinearities within density functional theory using M052X/6-31+G* level of approximation were also conducted for the considered series of compounds.

Luminescent lanthanide complexes for advanced photonic applications

The lanthanide compounds containing unsymmetrical β-diketone with [2.2]paracyclophane moiety in particular the europium complex with three [1-(4-[2.2]paracyclophanyl)]-3-phenylpropane-1,3-dione and 1,10-phenanthroline has been synthesized for the first time. The optical properties of [2.2]paracyclophane-derived ligands (symmetrical β-diketones and their respective N-phenylimines) as well as those of the europium complex were studied by UV-visible and luminescence spectroscopy. The diastereomers (racemic chiral, (R*,R*)- and achiral meso, (R,S)-) of the β-diketones and their respective N-phenylimines exhibit quite identical absorption spectra with intense broad band centered at 360 and 380 nm, respectively. The designed blue-emitting unsymmetrical β-diketone acts as a very efficient sensitizer of the EuIII emission and does so in the near-UV region. The introduction of [2.2]paracyclophane moiety in the β-diketones allows to expand the excitation wavelength of the lanthanide complex up to 500 nm and to obtain the relatively high overall quantum yield for the europium ion.

The correlation between SHG efficiency and structural peculiarities of [2.2]paracyclophane derivatives

ABSTRACT Nonlinear optical properties of 24 derivatives of [2.2]paracyclophane (pCp) have been analyzed. The set of the compounds studied include such classes as β-diketones, formyl-metoxy and formyl-hydroxy derivatives of pCp, pCp-Cr(CO)3, imines including Schiff bases. All molecules studied exhibit second harmonic generation ability, the efficiency of which was measured by the powder technique. In order to elucidate the role of intramolecular charge transfer due to transannular interaction in pCp the DFT calculations of the number of benzene analogues have been performed as well. For the first time the diastereomeric approach for the design of NLO materials was proposed and successfully utilized.