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Metal ions can serve as a centre of molecular motions due to their coordination geometry, reversible bonding nature and external stimuli responsiveness. Such essential features of metal ions have been utilized for metal-mediated molecular machines with the ability to motion switch via metallation/demetallation or coordination number variation at the metal centre; however, motion switching based on the change in coordination geometry remain largely unexplored. Herein, we report a PtII-centred molecular gear that demonstrates control of rotor engagement and disengagement based on photo- and thermally driven cis–trans isomerization at the PtII centre. This molecular rotary motion transmitter has been constructed from two coordinating azaphosphatriptycene rotators and one PtII ion as a stator. Isomerization between an engaged cis-form and a disengaged trans-form is reversibly driven by ultraviolet irradiation and heating. Such a photo- and thermally triggered motional interconversion between engaged/disengaged states on a metal ion would provide a selector switch for more complex interlocking systems.

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Background: The development of new surgical instruments and devices has facilitated the performance of esophagojejunostomy after total gastrectomy. However, total prevention of dehiscence of anastomoses remains difficult. We introduced a new procedure for esophagojejunostomy using a circular stapler, requiring sacrifice of only a small part of the jejunum. Methods: The study group comprised 390 consecutive patients who underwent reconstruction by Roux-en-Y esophagojejunostomy, performed with a circular stapler, sacrificing a small part of the jejunum after total gastrectomy. We assessed anastomotic leakage and anastomotic stenosis after surgery. Results: Only 2 patients (0.5%) had leakage and 4 (1.0%) had anastomotic stenosis after reconstruction. All the patients were cured by conservative therapy. Conclusions: Esophagojejunostomy performed with a circular stapler after total gastrectomy, with sacrifice of only a small part of the jejunum, is a useful and easy procedure, with a leakage rate of 0.5%.