Molecular Modeling of Enantioseparation of Phenylazetidin Derivatives by Cyclodextrins

β-Lactams are one of the most widely used types of antibiotics. As β-lactams are chiral, the enantiomeric separation of these compounds was investigated using cyclodextrins, frequently used as chiral separators. Molecular modeling methods were utilized in order to predict possible enantioseparation of four model compounds. Our results revealed that permethylated β-cyclodextrin is more likely to chirally separate the phenylazetidin derivates than the parent β-cyclodextrin. LC experiments using cyclodextrin as chiral stationary phase in most cases confirmed our prediction; however, more experiments and statistical evaluation of the results are needed in order to judge the prediction power of the molecular dynamic method.     

On the stability of a variety of organic photovoltaic devices by IPCE and in situ IPCE analyses - the ISOS-3 inter-laboratory collaboration

This work is part of the inter-laboratory collaboration to study the stability of seven distinct sets of state-of-the-art organic photovoltaic (OPV) devices prepared by leading research laboratories. All devices have been shipped to and degraded at RIS?-DTU up to 1830 hours in accordance with established ISOS-3 protocols under defined illumination conditions. In this work, we apply the Incident Photon-to-Electron Conversion Efficiency (IPCE) and the in situ IPCE techniques to determine the relation between solar cell performance and solar cell stability. Different ageing conditions were considered: accelerated full sun simulation, low level indoor fluorescent lighting and dark storage. The devices were also monitored under conditions of ambient and inert (N(2)) atmospheres, which allows for the identification of the solar cell materials more susceptible to degradation by ambient air (oxygen and moisture). The different OPVs configurations permitted the study of the intrinsic stability of the devices depending on: two different ITO-replacement alternatives, two different hole extraction layers (PEDOT:PSS and MoO(3)), and two different P3HT-based polymers. The response of un-encapsulated devices to ambient atmosphere offered insight into the importance of moisture in solar cell performance. Our results demonstrate that the IPCE and the in situ IPCE techniques are valuable analytical methods to understand device degradation and solar cell lifetime.     

Functionalisation of lanthanide complexes via microwave-enhanced Cu(I)-catalysed azide-alkyne cycloaddition

Cu(I)-catalysed azide-alkyne cycloaddition reactions were used to functionalise lanthanide(III)-complexes (Ln; La, Eu and Tb) incorporating alkyne or azide reactive groups. Microwave irradiation significantly accelerated the reactions, enabling full conversion to the triazole products in some cases in 5 min. Alkyl and aryl azides and alkyl and aryl alkynes could all serve as coupling partners. These reaction conditions proved efficient for cyclen-tricarboxylates and previously unreactive cyclen-tris-primary amide chelates. The synthesis of heterobimetallic (Eu/Tb, EuTb17 and Eu/La, EuLa17) and heterotrimetallic (Eu/La/Eu) complexes was achieved in up to 60% isolated yield starting from coumarin 2-appended alkynyl complexes Tb16 or La16 and an azido-Eu complex Eu4, and bis-alkynyl La-complex La5 and Eu4, respectively. EuTb17 displayed dual Eu(III) and Tb(III)-emission upon antenna-centred excitation.     

Rhenium complexes bearing phosphole-pyridine chelates: simple molecules with large chiroptical properties

The synthesis and chiroptical properties of chiral rhenium complexes bearing mono- or di-topic phosphole ligands are described.     

Thermoanalytical method for predicting the hydration effect permanency of dermal semisolid preparations

Our aim was to develop potential dermal drug delivery systems (DDSs) with a good and lasting moisturizing effect. Lyotropic liquid crystals (LLCs), gel-emulsions and hydrogels were investigated by means of thermogravimetry, which can give information about the structure of these preparations, and we could study the water binding mechanisms indirectly in them. We found that the preparations with a complex structure and strong water bonds hydrate the skin well and lastingly by in vivo tests. Since the thermoanalytical results correlate with the in vivo test results, this method could be suited for predicting the moisturizing effect of the vehicles and provide the possibility to select the potential semisolid DDSs for in vivo tests cost and time effectively.     

Optimal Mal’tsev conditions for congruence modular varieties

For varieties, congruence modularity is equivalent to the tolerance intersection property, TIP in short. Based on TIP, it was proved in [5] that for an arbitrary lattice identity implying modularity (or at least congruence modularity) there exists a Mal’tsev condition such that the identity holds in congruence lattices of algebras of a variety if and only if the variety satisfies the corresponding Mal’tsev condition. However, the Mal’tsev condition constructed in [5] is not the simplest known one in general. Now we improve this result by constructing the best Mal’tsev condition and various related conditions. As an application, we give a particularly easy new proof of the result of Freese and Jónsson [11] stating that modular congruence varieties are Arguesian, and we strengthen this result by replacing “Arguesian” by “higher Arguesian” in the sense of Haiman [18]. We show that lattice terms for congruences of an arbitrary congruence modular variety can be computed in two steps: the first step mimics the use of congruence distributivity, while the second step corresponds to congruence permutability. Particular cases of this result were known; the present approach using TIP is even simpler than the proofs of the previous partial results.Dedicated to the memory of Ivan RivalReceived February 12, 2003; accepted in final form August 5, 2004.This revised version was published online in August 2005 with a corrected cover date.     

Chemistry of indoles carrying a basic function. Part 8: A new approach to the ergoline skeleton

Starting from N-pivaloyl-Uhle's ketone a new synthetic approach to the ergoline skeleton has been elaborated. Ring D of the tetracyclic skeleton was formed by an intramolecular Dieckmann-condensation of a diester, obtained in a Reformatsky reaction of a properly substituted derivative of N-pivaloyl Uhle's ketone followed by elimination of water.     

Design of a colicin E7 based chimeric zinc-finger nuclease

Colicin E7 is a natural bacterial toxin. Its nuclease domain (NColE7) enters the target cell and kills it by digesting the nucleic acids. The HNH-motif as the catalytic centre of NColE7 at the C-terminus requires the positively charged N-terminal loop for the nuclease activity—offering opportunities for allosteric control in a NColE7-based artificial nuclease. Accordingly, four novel zinc finger nucleases were designed by computational methods exploiting the special structural features of NColE7. The constructed models were subjected to MD simulations. The comparison of structural stability and functional aspects showed that these models may function as safely controlled artificial nucleases. This study was complemented by random mutagenesis experiments identifying potentially important residues for NColE7 function outside the catalytic region.     

Microwave‐Promoted Efficient Synthesis of 2‐Phosphabicyclo[2.2.2]octadiene‐ and Octene‐2‐oxides under Solvent‐Free Conditions in Diels–Alder Reaction

The microwave‐induced and solvent‐free Diels–Alder reaction of 1,2‐dihydrophosphinine oxides (1 and 5) and dimethyl acetylenedicarboxylate or N‐phenylmaleimide afforded 2‐phosphabicyclo[2.2.2]octadiene‐ (2 and 6) and phosphabicyclo[2.2.2]octene oxides (4 and 7), respectively, almost quantitatively and in a fast reaction in an ecofriendly manner.     

Thermal analysis of starch for realizing embedded channel in low temperature co-fired ceramic

The rapidly developing biotechnology, automotive industry, chemical and environmental fields have increasing needs for analytical systems with desires such as smaller sizes, lower sample volumes. Reduction in size results in further requirements in functionalities such as multi-sensor devices with low cost. These microsystems usually contain three-dimensional structures. In the fabrication of microfluidic devices ensuring a well-shaped channel is a challenge. During firing of the low temperature co-fired ceramic (LTCC) substrate, these embedded structures tend to deform and sag because the green glass–ceramic material is very weak. Starch was used as sacrificial volume material (SVM) to support the embedded structures of the LTCC during lamination and sintering. As a consequence of burnout, the increased fraction of evolving gases from SVM requires an adequate adaptation of the firing process to control starch degradation and provide a residue-free burnout. Using thermal analysis techniques and describing degradation kinetics of SVM, a new heating profile is demonstrated which insures complete starch burnout without damaging the LTCC structures.