Three pentacene dimers have been synthesized to investigate the effect of molecular rotation and rotational conformations on singlet fission (SF). In all three dimers, the pentacene units are linked by...

The synthesis of the asymmetric ligand 3phenyl-1-(pyridin-2-yl)-1H-pyrazol-5-amine (L1) and its single-crystal X-ray structure are reported. L1 displays crystallographic symmetry (orthorhombic, Pccn) higher than its molecular symmetry (point group C 1 ) and also displays supercooling, with a difference in the melting and solidification points of over 100 °C. Upon complexation with ZnCl 2 , L1 engages in both primary cation and secondary anion coordination via hydrogen bonding, and the complex exhibits a room-to-low-temperature single crystal-to-crystal phase transition. The ZnCl 2 complex becomes a birefringent fluid mixed with crystalline domains at high temperatures, as detected by polarized optical microscopy. Examination of the photoluminescence properties showed that the emission intensity increased and a pronounced bathochromic shift was observed in the emission maximum upon going from solution to the solid state, for both the ligand and complex, consistent with aggregation-induced emission behavior.

Nickel-mediated Yamamoto coupling provides a concise and efficient synthesis of triphenylene derivatives, including electron-deficient discotic mesogens.

The synthesis and single crystal structures of 3-phenyl-1-(pyridin-2-yl)-1<i>H</i>-pyrazol-5-amine (<b>L1</b>) and its complex with ZnCl₂are reported. <b>L1</b> exhibits supercooling, with a difference in melting and solidification points of over 100 ^oC. The complex [<b>L1</b>ZnCl₂] has a room-to-low temperature single crystal-to-crystal phase transition in the solid state, while a birefringent fluid phase mixed with crystalline domains is observed at high temperatures. Significant fluorescence enhancement is observed upon formation of the ZnCl₂ complex.

The design and synthesis of urea-based systems suitable for selective anion recognition has demonstrated potential for environmental remediation. These systems act as a double hydrogen-bond donor to anion acceptors, however, the availability of the carbonyl group to also act as a hydrogen-bond acceptor has posed as an optimization challenge. One approach to address this obstacle is to design preorganized coordination complexes that decrease the accessibility of the carbonyl group, yet are still capable of anionic hydrogen bonding by secondary [a]

A variety of biaryl polyketides exhibit remarkable bioactivities. However, their synthetic accessibility is often challenging. Herein, the enantioselective preparation and synthetic application of an axially chiral 2,2'-biphenol building block is outlined that represents a common motif of these intriguing natural products. Based on the highly regioselective and scalable bromination of a phenol precursor, a coupling process by Lipshutz cuprate oxidation was developed. A copper-mediated deracemization strategy proved to be superior to derivatization or kinetic resolution approaches. Key steps in the overall building block synthesis were rationalized through DFT studies. Utilizing the 2,2'-biphenol, a highly diastereoselective five step synthesis of formerly unknown (+)-di-epi-gonytolide A was developed, thus showcasing the building block's general potential for the synthesis of natural products and their derivatives. En route, the first enantioselective construction of a chromone dimer intermediate was established.

Author(s) of this paper may load this reprint on their own web site or institutional repository provided that this cover page is retained. Republication of this article or its storage in electronic databases other than as specified above is not permitted without prior permission in writing from the IUCr.For further information see http://journals.iucr.org/services/authorrights.html Acta Cryst. (2017 Benzothiazole derivatives are a class of privileged molecules due to their biological activity and pharmaceutical applications. One route to these molecules is via intramolecular cyclization of thioureas to form substituted 2-aminobenzothiazoles, but this often requires harsh conditions or employs expensive metal catalysts. Herein, the copper ( ) is required for the cyclization to proceed. As such, this study provides further mechanistic insight into the role of the metal cations in these transformations.

e18503 Background: This study examines the geographic distribution of clinical trials for common types of metastatic cancer in the United States and the accessibility of these trials to the general population. Methods: We accessed the ClinicalTrials.gov website and conducted a search for interventional clinical trials that were actively recruiting patients for diagnoses of metastatic lung, colon, pancreas, breast, and prostate cancers on November 25, 2022. We identified unique zip codes for all the clinical trials offered and calculated the U.S. population living within 50 miles of a clinical trial site using geographic information system software based on 2020 census data. We created maps for each cancer type, demonstrating the geographic distribution of clinical trial access in the United States. Results: We found a significant number of clinical trials providing access for most Americans diagnosed with the most common types of metastatic cancer. The majority of the United States population lives within 50 miles of a clinical trial. The access varied by cancer type studied, from 75.0% of the United States population for metastatic colon cancer to 90.2% for metastatic lung and breast cancers. See table for details. Conclusions: When considering the accessibility of these trials, we found that a large proportion of the United States population lived within 50 miles of a clinical trial site. This suggests that while many clinical trials are available, they may not be evenly distributed across the country and may not be accessible to all individuals. [Table: see text]