Optical implementation of entangled multi-spin states in a CdTe quantum well

Ultrafast optical pulses and coherent techniques are used to create spin entangled states of non-interacting electrons bound to donors in a CdTe quantum well. Our method, relying on the exchange interaction between optically excited holes and the impurities, can in principle, be applied to entangle a large number of spins. Results are presented for resonant excitation of localized excitons below the gap, and above the gap where the signatures of entanglement are significantly enhanced.     

Recent Advances and Trends in Chemical CPP–Drug Conjugation Techniques

This review summarizes recent developments in conjugation techniques for the synthesis of cell-penetrating peptide (CPP)–drug conjugates targeting cancer cells. We will focus on small organic molecules as well as metal complexes that were used as cytostatic payloads. Moreover, two principle ways of coupling chemistry will be discussed direct conjugation as well as the use of bifunctional linkers. While direct conjugation of the drug to the CPP is still popular, the use of bifunctional linkers seems to gain increasing attention as it offers more advantages related to the linker chemistry. Thus, three main categories of linkers will be highlighted, forming either disulfide acid-sensitive or stimuli-sensitive bonds. All techniques will be thoroughly discussed by their pros and cons with the aim to help the reader in the choice of the optimal conjugation technique that might be used for the synthesis of a given CPP–drug conjugate     

Discovery of potent inhibitors of human β-tryptase from pre-equilibrated dynamic combinatorial libraries

Pre-equilibrated dynamic combinatorial libraries based on acyl hydrazone interchange of peptide-derived hydrazides and di- and tri-aldehydes have been used to discover potent inhibitors with nanomolar affinities for β-tryptase. To identify potent inhibitors the activity of the full library containing 95 members was compared with those of sub-libraries in which individual building blocks were missing. The most active library members contain a rigid central aromatic scaffold with three cationic peptide arms. The arms of the best inhibitors also contained a tailor-made GCP oxoanion binding motif attached to a lysine side chain. The most potent tri-armed hydrazones with peptide arms GKWR or GKWK(GCP) were shown to inhibit β-tryptase (K _i ca. 10–20 nM) reversibly, non-competitively and selectively (compared to related serine proteases, e.g. trypsin and chymotrypsin), most likely by binding to the protein surface, also in agreement with molecular modelling calculations. These new inhibitors are one order of magnitude more efficient than related tetravalent inhibitors obtained from previous work on a split-mix-combinatorial library and were identified with significantly less effort, demonstrating the usefulness of this approach for the identification of enzyme inhibitors in general.     

The Photochemistry of the (Cycloalkene)(hydro)(trispyrazolylborato)iridium Complexes [Ir(η4-cod)(TpMe2)] and [Ir(η2-coe)H2(TpMe2)]: the Formation of [IrH4(TpMe2)] and [Ir(CO)H2(TpMe2)]

Photolysis of [Ir(η²-coe)H₂(Tp^Me2)] ( 1 ; Tp^Me2=hydrotris(3,5-dimethylpyrazolyl)borato, coe=(Z)-cyclooctene) in CH₃OH gives a mixture of [IrH₄(Tp^Me2)] ( 4 ) and [Ir(CO)H₂(Tp^Me2)] ( 5 ) in a ca. 1 : 1 ratio. Mass-spectral analysis of the distillate of the reaction mixture at the end of the photolysis shows the presence of coe. When pure CD₃OD is used as solvent, the deuteride complexes [IrD₄(Tp^Me2)] ((D₄)- 4 ) and [Ir(CO)D₂(Tp^Me2)] ((D₂)- 5 ) are obtained. Also the photolysis of [Ir(η⁴-cod)(Tp^Me2)] ( 3 ) (cod=cycloocta-1,5-diene) gives 4 and 5 . A key feature of this photoreaction is the intramolecular dehydrogenation of cod with formation of cycloocta-1,3,5-triene, detected by mass spectroscopy at the end of the photolysis. Labeling experiments using CD₃OD show that the hydrides in 4 originate from MeOH. When ¹³CH₃OH is used as solvent, [Ir(¹³CO)H₂(Tp^Me2)] is formed demonstrating that CH₃OH is the source of the CO ligand. The observation that the photolysis of both 1 and 3 give the same product mixture is attributed to the formation of a common intermediate, i.e., the coordinatively unsaturated 16e⁻ species {IrH₂(Tp^Me2)}.     

The Photochemistry of (Diene)(hydro)[tris(3,5-dimethylpyrazolyl)borato]rhodium Complexes,Preliminary Communication

The photochemical rearrangement of [Rh(η⁴-1,5-cod)Tp^Me2](Tp^Me2=hydrotris(3,5-dimethylpyrazolyl)borato, 1,5-cod=cycloocta-1,5-diene) to the new compound [Rh(η⁴-1,3-cod)Tp^Me2] ( 2 ) is described. The characterization of 2 was carried out using ¹H-, ¹³C-, and ¹⁰³Rh-HMQC-NMR spectroscopy. Photolysis of 2 is a versatile entry point into the organometallic chemistry of the {RhTp^Me2} fragment as it can be used to produce a) hydrido-carbonyl ([Rh(CO)H₂Tp^Me2]), b) hydrido-phenyl-phosphite ([RhH(Ph)(P(OMe)₃)Tp^Me2]), and c) ethoxide-hydrido-phosphite ([RhH(OEt)(P(OMe)₃)Tp^Me2]) complexes.