A bottleneck in fragment-based lead development is the lack of systematic approaches to elaborate the initial fragment hits, which usually bind with low affinity to their target. Herein, we describe an analysis using X-ray crystallography of a diverse library of compounds prepared using microscale parallel synthesis. This approach yielded an 8-fold increase in affinity and detailed structural information for the resulting complex, providing an efficient and broadly applicable approach to early fragment development.

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Direct integration of III-V semiconductor light sources on silicon is an essential step towards the development of portable, on-chip infrared sensor systems. Driven by the presence of characteristic molecular fingerprints in the mid-infrared spectral region, such systems may have a wide range of applications in infrared imaging, gas sensing and medical diagnostics. This paper reports on the integration of an InAs virtual substrate and high crystalline quality InAs/InAsSb multi-quantum wells on Si using a three-stage InAs/GaSb/Si buffer layer. It is shown that the InAs/GaSb interface demonstrates a strong dislocation filtering effect. A series of strained AlSb/InAs dislocation filter superlattices were also used, resulting in a low surface dislocation density of approximately 4 × 10 7 cm -2 . The InAs/InAsSb wells exhibited strong photoluminescence signal at elevated temperatures.Analysis of these results indicate that radiative recombination is the dominant recombination mechanism, making this structure promising for fabricating MIR Si-based sensor systems.The presence of fundamental vibration absorption bands of several gaseous species in the 2 to 12 μm mid-infrared (MIR) electromagnetic spectral region presents high technological potential for a wide range of applications, including absorption spectroscopy, environmental monitoring, chemical sensing and medical diagnostics. MIR silicon (Si) photonics has attracted great interest due to its potential to realize lab-on-chip optoelectronic systems. Si wafers have numerous advantageous properties, such as their large area, improved robustness and low cost. 1 Fabrication _____________________________

GaSb-based materials can be used to produce high performance photonic devices operating in the technologically important mid-infrared spectral range. Direct epitaxial growth of GaSb on silicon (Si) is an attractive method to reduce manufacturing costs and opens the possibility of new applications, such as lab-on-a-chip MIR photonic integrated circuits and monolithic integration of focal plane arrays (FPAs) with Si readout integrated circuits (ROICs). However, fundamental material dissimilarities, such as the large lattice mismatch, polar-nonpolar character of the III-V/Si interface and differences in thermal expansion coefficients lead to the formation of threading dislocations and antiphase domains, which effect the device performance. This work reports on the molecular beam epitaxial growth of high quality GaSb-based materials and devices onto Si. This was achieved using a novel growth procedure consisting of an efficient AlSb interfacial misfit array, a two-step GaSb growth temperature procedure and a series of dislocation filter superlattices, resulting in a low defect density, anti-phase domain free GaSb buffer layer on Si. A nBn barrier photodetector based on a type-II InAs/InAsSb superlattice was grown on top of the buffer layer. The device exhibited an extended 50 % cutoff wavelength at 5.40 μm at 200 K which moved to 5.9 μm at 300 K. A specific detectivity of 1.5 x10 10 Jones was measured, corresponding in an external quantum efficiency of 25.6 % at 200 K.

We present the results of an investigation into the growth of InGaSb/GaAs quantum dots (QDs) by molecular beam epitaxy using migration-enhanced epitaxy. Surface atomic force microscopy and cross-sectional transmission electron microscopy show that the QDs undergo a significant change in morphology upon capping with GaAs. A GaAs 'cold capping' technique was partly successful in preserving QD morphology during this process, but strong group-V intermixing was still observed. Energy-dispersive x-ray spectroscopy reveals that the resulting nanostructures are small 'core' QDs surrounded by a highly intermixed disc. Temperature varying photoluminescence (PL) measurements indicate strong light emission from the QDs, with an emission wavelength of 1230 nm at room temperature. Nextnano 8×8 k.p calculations show good agreement with the PL results and indicate a low level of group-V intermixing in the core QD.