The long and winding road to planar carbon

Plat koolstof vormt het voornaamste doelwit van het in dit proefschrift beschreven onderzoek. In het algemeen hebben verbindingen met een tetraedrisch koolstofatoom een lagere energieinhoud dan hun platte soortgenoot (het energieverschil tussen bv. Plat en tetraedisch methaan is 100-250k cal /mol ) . Stabiliserende factoren, zoals Π-akspetoren, ς- donoren en kleine ringen, kunnen echter zorgen voor een aanzienlijke vermindering van het energieverschil tussen een platte en de overeenkomstige tetraedische struktuur (hoofdstuk 1) Verbindingen met een plat koolstofatoom zijn tot op heden echter nog niet gesynthetiseerd. ... Zie: Samenvatting

The synthesis of liquid-crystalline diacrylates derived from cyclohexane units

\u3cp\u3eOrdered polymeric networks are produced via the photopolymerization of liquid-crystalline (LC) diacrylates. When these diacrylates are derived from aromatic rings, the networks show UV-light instability. In order to overcome this problem, the cyclohexane analogues of two of these LC diacrylates were synthesized. The newly formed molecules exhibit much lower UV absorption than their aromatic analogues but also completely different phase behaviour. One of them showed a highly viscous LC phase, the other lacks LC properties.\u3c/p\u3

The effect of substituents on the helical twisting power of aldol condensation products of menthone

\u3cp\u3eThe helical twisting powers of the E-isomers of aldol condensation products of menthone and aromatic aldehydes are higher than those of the Z-isomers. In order to find out which chiral centre of these menthone derivatives is responsible for the value of the helical twisting in both isomers, the E-isomers of aldol condensation products of 3-methylcyclohexanone and 2-isopropylcyclohexanone were prepared and photoisomerized to form Z-isomers. The physical properties of these species were determined. It was concluded that the strong helical twisting power of the E-isomers of the derivatives of menthone is caused by the chiral carbon atom containing the methyl group in the ring. The relatively low helical twisting power of the Z-isomers and the composition of the E-Z isomers in the photostationary state are determined mainly by the other chiral centre containing the isopropyl group.\u3c/p\u3

A Concise Synthetic Approach to Highly Reactive Click-to-Release Trans-Cyclooctene Linkers

An increase of the click-to-release reaction rate between cleavable trans-cyclooctenes (TCO) and tetrazines would be beneficial for drug delivery applications. In this work, we developed a short and stereoselective synthesis route towards highly reactive sTCOs that serve as cleavable linkers, affording quantitative tetrazine-triggered payload release. In addition, the 5-fold more reactive sTCO exhibited the same in vivo stability as the parent TCO linker when used as antibody linker in circulation in mice

Click to release: instantaneous doxorubicin elimination upon tetrazine ligation

Eliminated without a trace: The fastest click reaction, the highly selective inverse-electron-demand Diels-Alder reaction, has been modified to enable selective bioorthogonal release. Thus, the click reaction of a tetrazine with a drug-bound trans-cyclooctene caused the instantaneous release of the drug and CO2 (see scheme). One possible application is the chemically triggered release, and thereby activation, of a drug from a tumor-bound antibody-drug conjugate

Spectra and electrical properties of soluble partially alkyl-substituted oligomers of thiophene up to 11 rings

A series of strictly a, a'-coupled oligomers of thiophene contg. 3,4,5,6,7,9, and 11 rings and provided with 0 to 5 side groups (Bu, n-dodecyl or tert-butyl) were prepd. and their m.ps., solubilities in chloroform, UV-visible absorption and emission spectra of both solns. and solids, and conductivities after doping with iodine have been measured.. The dependence of the conjugation length on the no. of rings, and on the no., length, and position of side groups is discussed. [on SciFinder (R)

Pretargeting kit, method and agents used therein

\u3cp\u3eDescribed is a pretargeting method, and related kits, for targeted medical imaging and/or therapeutics, wherein use is made of abiotic reactive chemical groups that exhibit bio-orthogonal reactivity towards each other. The invention involves the use of [4+2] inverse electron demand (retro) Diels-Alder chemistryin providing the coupling between a Pre-targeting Probe and an Effector Probe. To this end one of these probes comprises an electron-deficient tetrazine or other suitable diene, and the other an E-cyclooctene which has one or more axial substituents.\u3c/p\u3

A New 31P NMR Method for the Enantiomeric Excess Determination of Alcohols, Amines and Amino Acid Esters.

Diastereoisomeric ester and amide derivatives of phosphoric acid chloride 2 show well separated signals in the 31P NMR spectra allowing accurate e.e. determination of chiral alcohols, esters of amino acids and amines.

Pretargeting kit, method and agents used therein

\u3cp\u3eDescribed is a pretargeting method, and related kits, for targeted medical imaging and/or therapeutics, wherein use is made of abiotic reactive chemical groups that exhibit bio-orthogonal reactivity towards each other. The invention involves the use of [4+2] inverse electron demand (retro) Diels-Alder chemistry in providing the coupling between a Pre-targeting Probe and an Effector Probe. To this end one of these probes comprises an electron-deficient tetrazine or other suitable diene, and the other an E-cyclooctene which has one or more axial substituents.\u3c/p\u3