Single‐Point Remote Control of Flapping Motion in Clothespin‐Shaped Bimetallic Palladium Complexes Based on the N(sp2)–N(sp3) Interconversion in Amide Functionalities

The synthesis, structure, and flapping motion of clothespin‐shaped binuclear trans‐bis(salicylaldiminato)palladium(II) complexes (anti‐ 1 ) with 4‐azaheptamethylene linkers bearing amide ( a – g ), urethane ( h ), or urea ( i ) functionalities are described in this report. Various 2D ¹H NMR experiments and XRD analyses indicate that the amide‐ and urethane‐linked anti‐ 1 a , b , d – h complexes exist as equilibrated mixtures of major and minor conformers I and II in CDCl₃, whereas the complexes anti‐ 1 c and i were observed as a single species. The mapping of NOESY cross‐peaks between conformers I and II revealed that the equilibration of the major and minor conformers of anti‐ 1 a , b , d – h proceeds by two pathways, namely a nonrotatory flapping motion of the coordinated blades and a nonflapping rotation of C?N bonds, whereas the equilibration of anti‐ 1 c proceeds by simultaneous flapping and rotation motions. Kinetic studies carried out by means of ¹H–¹H EXSY experiments revealed that 1) the ΔG^≠_298K values for the flapping motion are controlled remotely by the steric and electronic effects of the RCON functionalities and 2) the activation parameters for the nonrotatory flapping process are identical to those for the nonflapping peptide rotation in the complexes anti‐ 1 a,b,d – h , which indicates that the present multistep conformational transformation induced by the flapping motion is controlled by the rate‐determining pyramidalization/depyramidalization (i.e., sp²/sp³ interconversion) of the nitrogen atoms of the functionalities. The static and controllable molecular mobility of anti‐ 1 bearing peptide linkers has been discussed by comparison with the dynamic behavior of its analogues anti‐ 2 – 4 with flexible polymethylene linkers.     

Algorithms for image recovery calculation in extended single-shot phase-shifting digital holography

Optical Review - The single-shot phase-shifting method of image recovery using an inclined reference wave has the advantages of reducing the effects of vibration, being capable of operating in real...     

Practical one-pot conversion of aryl bromides and β-bromostyrenes into aromatic nitriles and cinnamonitriles

Various aryl bromides were efficiently converted into the corresponding aromatic nitriles in good yields by the treatment with Mg turnings and subsequently DMF, followed by treatment with molecular iodine and aq NH₃. The same treatment of aryl bromides, which are weakly reactive to Mg turnings, with ⁱPrMgCl·LiCl and subsequently DMF, followed by the treatment with molecular iodine and aq NH₃ also afforded the corresponding aromatic nitriles in good yields. On the other hand, when N-formylpiperidine was used instead of DMF, p-substituted β-bromostyrenes were converted into the corresponding p-substituted cinnamonitriles, i.e., α,β-unsaturated nitriles, in good to moderate yields by the same procedure. The reactions were carried out by means of a simple experimental procedure and did not require any toxic metal cyanides or expensive rare metals. Therefore, the present reactions are practical and environmentally benign one-pot methods for the preparation of aromatic nitriles, cinnamonitriles, and aliphatic nitriles from aryl bromides, β-bromostyrenes, and alkyl bromides, respectively, through the formation of Grignard reagents and their DMF or N-formylpiperidine adducts.     

Stereochemical assignment of topsentolide C2 by stereodivergent synthesis of its four diastereomers

Four diastereomers of topsentolide C₂, a cytotoxic nine-membered lactone isolated from the marine sponge Topsentia sp., were synthesized stereodivergently from a common chiral seco acid by the combined use of the Yamaguchi and Mitsunobu lactonizations. Comparison of the NMR spectra of the four diastereomers with those of an authentic sample of topsentolide C₂ led to the stereochemical determination of topsentolide C₂ as 8R, 11S, and 12S.     

Chemically Functionalized Two‐Dimensional Carbon Materials

Nanographenes (NGs), also known as graphene quantum dots, have recently been developed as nanoscale graphene fragments. These nanocarbon species can be excited with UV light and emit light from the UV‐to‐visible region. This photoemission has received great attraction across multiple scientific fields. NGs can be produced by cutting off carbon sources or fusing small organic molecules to grow graphitic structures. Furthermore, the organic synthesis of NGs has been intensely studied. Recently, the number of research papers on postsynthetic modification of NGs has gradually increased. Installed organic groups can tune the properties of NGs and provide new functionalities, opening the door for the development of sophisticated carbon‐based functional materials. This review sheds light on recent progress in the postsynthetic modification of NGs and provides a brief summary of their production methods.