Triorganoón(IV)-vegyületek termikusan indukált szilárd és olvadékfázisú csoport-vándorlással végbemenő diszmutációs reakciójának vizsgálata és szerkezeti alapokon nyugvó osztályozása = Study of the thermally induced group-migration reaction of the triorganotin(IV)-complexes in the solid-state and melt and the classification of these reactions based on the X-ray structural data

A pályázatban a triorganoón(IV)-komplexek diszmutációs átalakulását tanulmányoztam. Bebizonyítottam, hogy a trimetilón(IV)-komplexek szintézise és átkristályosítása során tapasztalt instabilitást a metil-csoportok vándorlásával végbemenő diszmutációs átalakulás okozza. Előállítottam a trimetilón(IV)-kupferronát, [Me3Sn(cupf)]4, -tropolonát, Me3Sn(trop), és -benzoát Me3Sn(bz) komplexeket. Kimutattam, hogy a termikusan indukált metil-vándorlással végbemenő diszmutációs reakcióban a Me3Sn(O,O-donor) komplex kristályai Me2Sn(O,O-donor)2 kristályok és illékony Me4Sn képződése során demetileződnek. A Me3Sn(bz) demetilezése során a végső diszmutációs termék a dimer {[Me2Sn(bz)]2O}2 disztannoxán volt. A trimetilón(IV)-komplexek kristályszerkezetének ismerete lehetővé tette a szilárd-fázisú diszmutációs reakciók értelmezését. Megállapítottam, hogy a [Me3Sn(cupf)]4 tetramer és Me3Sn(bz) koordinációs polimer demetilezése a kristályszerkezet összeomlásán keresztül valósult meg. Ezzel szemben, a Me3Sn(trop) kristályszerkezetének értelmezése valószínűvé tette, hogy a megfigyelt diszmutációs átalakulás egy ciklikus bimolekuláris asszociátumon keresztül játszódik le. Munkám során bebizonyítottam, hogy a trimetilón(IV)-vegyületek szilárd és olvadékfázisban metil-csoport vándorlással végbemenő termikusan indukálható diszmutációs bomlást szenvednek. Azt is bizonyítottam, hogy a kristályszerkezetek ismeretében értelmezhetők ezek az átalakulások. | We demonstrated that the methyl-migrational dismutation process is a potential source of trimethyltin(IV)-complexes instability, which prevents the preparation of devised structures via crystallization. We reported the successful synthesis and X-ray structural determination of trimethyltin(IV)-cupferronate [Me3Sn(cupf)]4, -tropolonate Me3Sn(trop), and -benzoate Me3Sn(bz). We have also shown that the single crystals of these Me3Sn(O,O-donor) complexes demethylated into single crystals of Me2Sn(O,O-donor)2 and volatile Me4Sn. Interestingly, the final dismutation product of the Me3Sn(bz) demethylation was the dimeric {[Me2Sn(bz)]2O}2 distannoxane. The knowledge of the crystal structure of the trimethyltin(IV)-complexes provided a direct rationalisation of the solid-state dismutation reaction. We observed that the [Me3Sn(cupf)]4 tetramer and the Me3Sn(bz) coordination polymer demethylation proceeded with significant change of the molecular and crystal structure. In contrast, on the basis of the stacking pattern of the Me3Sn(trop) complex, it is reasonable to expect that the observed dismutation can occur through a cyclic bimolecular associate. Our work provided conclusive evidence for the occurrence of thermally induced degradation via methyl-group removal of triorganotins in the solid state. Moreover, we demonstrated that such rearrangements could be rationalized based on crystal structures

Önszerveződő fémorganikus vegyületek szintézise és szerkezeti jellemzése = Synthesis and structural characterization of self-assembled organometallic compounds

A SZTÉRIKUS HATÁS MEGNYILVÁNULÁSA PALLÁDIUMKOMPLEXEK ÖNSZERVEZŐDÉSÉBEN. Megfigyeltük, hogy 4,4?-bpy és különböző térigényű [Pd(NÇN)(NO3)2] komplexek reakciójában a kelátképző ligandum méretétől függően trimer vagy tetramer komplexek képződnek főtermékként. Megállapítottuk, hogy a legkisebb térigényű fémkomplexek (NÇN = etilén-diamin vagy homopiperazin) esetében is kimutatható trimer termék. Geometriai megfontolások alapján sztérikusan különböző koordinációs helyeket tartalmazó, új Ar-BIAN ligandumokat állítottunk elő. Kimutattuk, hogy nagy térigényű palládiumkomplexekkel való reakcióikban az elsődleges koordinációs helyet a terminális piridilcsoportok jelentik a sztérikusan gátolt kelátképző helyekkel szemben, ami a két koordinációs hely szigorúan konszekutív részvételében mutatkozik meg. Különböző térigényű palládiumkomplexek egyidejű jelenlétében a sztérikus hatás méret szerinti szelektív koordinációban nyilvánul meg. KATIONOK HATÁSA ÓNTARTALMÚ MAKROCIKLUSOK ÖNSZERVEZŐDÉSÉRE. A trimetilón(IV)-klorid reagálva a szupramolekuláris [Me3Sn(cupf)]4 tetramert eredményezi. Ezt a metatézist Na+-ionok jelenlétében megvalósítva, a képződött komplex dimetilón(IV) dimer, [Me2Sn(cupf)2]2. A tetramer metilcsoport vándorlással végbemenő diszmutációval alakul át dimerré és tetrametilónná. NMR vizsgálatokkal értelmeztük a tetramer dizmutációs átalakulását. Az organoón(IV) szupramolekulákra gyakorolt oldószerhatás nem szupramolekuláris izomer, hanem új szupramolekula kialakulását eredményezi. | STERIC EFFECTS IN THE SELF-ASSEMBLY OF Pd-COMPLEXES. We have found that the interaction of 4,4?-bpy with sterically different [Pd(NÇN)](NO3)2 complexes may result in either tetramers or trimers as major products. We have demonstrated that trimeric species are formed even with the sterically least congested tectons (NÇN = ethylenediamine or homopiperazine). Based on geometric considerations, we have prepared novel Ar-BIAN ligands with sterically different coordination sites. We have shown that the terminal pyridyl groups are preferred over the internal chelating nitrogen atoms in self-assembly with sterically demanding palladium complexes, which causes a strictly consecutive coordination of the metal complexes at the sterically different coordination sites. The steric effects manifest themselves in size-selective coordination when complexes of different bulkiness interact with the Ar-BIAN ligand. CATIONIC EFFECT IN THE SELF-ASSEMBLY OF TIN MACROCYCLES. The reaction of trimethyltin(IV)-chloride with cupferon results in a self-organized [Me3Sn(cupf)]4 tetramer. This metathesis carried out in the presence of Na+ ions provides dimethyltin(IV) dimer, [Me2Sn(cupf)2]2.The transformation of the tetramer involves a dismutation with methyl-migration. The mechanism of this transformation was analyzed by NMR methods. The solvent effects on the Sn(IV) supramolcules results in a new supramolecule rather than a supramolecular isomer

Mechanochemical synthesis of crystalline and amorphous digold(i) helicates exhibiting anion- and phase-switchable luminescence properties

For the first time, mechanochemical synthesis has been used for the preparation of crystalline and amorphous dinuclear gold(i) helicates, [Au2L2](X)2 (L = xantphos; X = CF3SO3, SCN, BF4 and PF6), that show anion- and phase-switchable luminescence properties. This solid-state approach provides strategies for developing switchable luminescent materials

A stimuli-responsive double-stranded digold(I) helicate

We report herein a stimuli-responsive dinuclear double stranded [Au2L2]2+ helicate assembled from gold(I) atoms and phenyl-substituted diphosphine ligands derived from a xanthene-type backbone (L). The conformational flexibility of the dinuclear [Au2L2]2+ helicate allows a diversity of molecular conformations and packing arrangements that lead to different solid-state emission colours. Blue (IB), bluish green (IIG) and yellow (IIIY) emitting crystalline and red emitting (IVR) amorphous forms of this double stranded [Au2L2]2+ helicate have been obtained by slight modification of the crystallization conditions. Different molecular conformations and packing arrangements of dinuclear double stranded [Au2L2]2+ helicates that result in different non-covalent interactions played the most significant role in tailoring the solid-state luminescence properties. On the basis of the single crystal structural data and photophysical studies, we found that an increasing number of intra- and mainly intermolecular noncovalent interactions locked and rigidified the twisted conformation of the double stranded [Au2L2]2+ helicate, and enhanced π-stacking between its aromatic units induced the red-shift in solid-state luminescence emission. The solid-state luminescence colour of this double stranded [Au2L2]2+ helicate can be switched reversibly from blue to red by external (mechanical and chemical) stimuli

Mechano-induced reversible colour and luminescence switching of a gold(I)-diphosphine complex

A gold(I)-diphosphine simultaneously exhibits reversible mechanochromism and mechanochromic luminescence. The mechanical grinding can trigger a transformation from a neutral mononuclear structure exhibiting white colour and blue photoluminescence to an ionic dinuclear structure with intramolecular aurophilic interaction exhibiting yellow colour and red emission

Unexpected formation of a fused double cycle trinuclear gold(i) complex supported by ortho-phenyl metallated aryl-diphosphine ligands and strong aurophilic interactions

The first homoleptic trinuclear arylgold(i) complex, [Au3(L')2](NO3) (3), based on an ortho-phenyl metallated aryl-diphosphine ligand (L' = o-C6H4PPh(C15H10O)PPh2), has been obtained through a new thermolytic reaction of the corresponding diauracycle, [Au2(L)2](NO3)2 (L = xantphos). The formation of 3 involves activation of the ortho-phenyl C-H bond of the xantphos ligands. The presence of Au-C bonds in this new gold-diphosphine cluster is not its only remarkable feature, since it also displays two 12-membered rings fused together and a linear {Au3} chain with aurophilic interactions. Complex 3 exhibits strong sky-blue luminescence that can be assigned to a triplet metal-metal (3MM) transition partially mixed with a ligand-to-metal-metal charge transfer (3LMMCT) transition related to the aurophilic bonding. This [Au3(L')2]+ triauracycle also shows AIEE-activity, and is a selective luminescent chemosensor for metal ions

A morpho-physiological approach differentiates bread wheat cultivars of contrasting tolerance under cyclic water stress

Leaf micromorphological traits and some physiological parameters with potential relevance to drought tolerance mechanisms were investigated in four selected winter wheat varieties. Plants were subjected to two cycles of drought treatment at anthesis. Yield components confirmed contrasting drought-sensitive and -tolerant behavior of the genotypes. Drought tolerance was associated with small flag leaf surfaces and less frequent occurrence of stomata. Substantial variation of leaf cuticular thickness was found among the cultivars. Thin cuticle coincided with drought sensitivity and correlated with a high rate of dark- adapted water loss from leaves. Unlike in Arabidopsis, thickening of the cuticular matrix in response to water deprivation did not occur. Water stress induced epicuticular wax crystal depositions preferentially on the abaxial leaf surfaces. According to microscopy and electrolyte leakage measurements from leaf tissues, membrane integrity was lost earlier or to a higher extent in sensitive than in tolerant genotypes. Cellular damage and a decline of relative water content of leaves in sensitive cultivars became distinctive during the second cycle of water deprivation. Our results indicate strong variation of traits with potential contribution to the complex phenotype of drought tolerance in wheat genotypes. The maintained mem- brane integrity and relative water content values during repeated water limited periods were found to correlate with drought tolerance in the selection of cultivars investigated