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This study presents photoresponsive, dynamic pseudorotaxane crystals composed of axle molecules containing biferrocene or ferrocene groups threaded through a dibenzo[24]crown-8 ether ring. A biferr...

Molecular machines and switches composed of flexible pseudorotaxanes respond to external stimuli, transducing incident energy into mechanical motions. This study presents thermo- and photoresponsive dynamic pseudorotaxane crystals composed of axle molecules containing ferrocene or ruthenocene groups threaded through dibenzo[24]crown-8 ether rings. The ruthenocene-containing pseudorotaxane exhibits a crystal-to-crystal thermal phase transition at 86 °C, which is much lower than that of the ferrocene-containing pseudorotaxane (128 °C). Single-crystal X-ray crystallography at various temperatures reveals the details of the structural changes, and shows that the bulky ruthenocene provides distortion in the pseudorotaxane structure to facilitate twisting of the axle molecule. A mixed ferrocene and ruthenocene pseudorotaxane crystal is applied to photomechanical conversion under 405 nm laser irradiation at 85 °C and provides a lifting force 6,400-times the weight of the crystal itself upon phase transition.

Crystalline phase transitions caused by external stimuli have been used to detect physical changes in the solid-state properties. This study presents the mechanical switching of crystals of ferrocene-containing rotaxane controlled by focused laser light. The expansion and contraction of the crystals can be driven by turning on and off laser light at 445 nm. The irradiation-induced expansion of the crystal involves elongation along the a, b and c axes at 30 °C, whereas heating of the crystal at 105 °C causes the shortening of c axis. The expansions reversibly occur and have the advantage of a rapid relaxation (reverse) process. Single-crystal X-ray crystallography reveals the detailed structural changes of the molecules, corresponding to a change in the size of the crystals on laser irradiation. This molecular crystal behaviour induced by laser irradiation, is demonstrated for the remote control of objects, namely, microparticle transport and microswitching in an electric circuit., Crystalline phase transition can be used to detect changes in the solid state properties of materials. Here, the authors describe the mechanical response of a crystal composed of ferrocene-containing rotaxane to laser irradiation.

A cellphone with TEMS Pocket software (referred to as user equipment) was employed to measure 4G Internet signals in May 2017. Key performance indicators of packet-switched transmission between the user equipment and 4G EnodeB base stations were used to calculate the cell range and area coverage probability of an LTE network. The measurement was performed at Oriental Institute of Technology, a university located in Banqiao District, New Taipei City, in Northern Taiwan. The measurements were collected in a 1.3 × 1 km area (south-north by east-west) in densely populated urban areas of Banqiao District. A total of 26 EnodeB base stations were involved; among them, 18 supported the 700 MHz band, 19 supported the 1800 MHz band, and 21 supported the 2600 MHz band. The results of data analysis determined that, when signal data from multiple EnodeB base stations were averaged and receiver sensitivity was −105dBm, the mean all-modulated and coding scheme weighted cell range was 0.27436km and the area coverage probability was 59.07% at 700 MHz; the mean range was 0.2812 km and the area coverage probability was 48.79% at 1800 MHz; the mean range was 0.3175 km and the area coverage probability was 41.63% at 2600 MHz.

This study investigated the dynamic photoresponse of pseudorotaxane crystals with azobenzene and ferrocenyl groups in the axle component. X-ray crystallography showed pseudorotaxanes with a methylazobenzene group and a dibromophenylene ring in the cyclic component to exhibit twisting of the trans-azobenzene groups at torsion angles of 17° and 38°, respectively. Repeated alternating laser irradiation of the crystals at 360 and 445 nm produced bending of 20–30° in opposite directions, with no evidence of decay. Under 445 nm irradiation, bending took place within 0.3 s. A crystal of nonsubstituted pseudorotaxane showed bending of only 2° under 360 nm irradiation due to multiple π–π interactions between the planar trans-azobenzene groups. The pseudorotaxane crystals have two chromophores, bent rapidly and reversibly on irradiation at rates depending on the molecular structure.

The measurement in this study was conducted using a TEMS Pocket engineering model test phone, through which the cell coverage and cell capacity of LTE were analyzed using the KPI parameters of packet switch (PS) between the 4G EnodeB base stations (BSs) and user equipment (UE). Of the 60 EnodeB BSs that were measured, 46 supported the 700 MHz band, 35 supported the 1800 MHz band, and 6 supported the 2600 MHz band. The analysis results for the measurement data showed that the modulation code scheme (MCS) cell range means for MCS (0)–MCS (28) in Banqiao District were approximately 0.2–0.91 km, with an overall MCS average of 0.45 km. Cell capacity was presented using downlink (DL) throughput; the analysis results illustrated that the average DL throughputs were roughly 5.37 Mb/s–49.71 Mb/s, and the overall MCS average throughput was 18.87 Mb/s. The signal-to-interference-plus-noise ratio (SINR) means for MCS (0)–MCS (28) were approximately −5.33–20.38 dB, and the overall MCS averaged SINR was approximately 6.04 dB. The reference signal received power (RSRP) means for MCS (0)–MCS (28) were approximately −111.86–−73.83 dBm, and the overall MCS averaged RSRP was approximately −94.09 dBm. Finally, the analysis and comparison of the theoretical values and actual measurement illustrated that the data curves for this study were consistent with the 3GPP specifications, with SINR and the theoretical curve achieving a correlation of up to 0.936, and the DL throughput and the theoretical curve achieving a correlation of up to 0.933.

Water-soluble polymers comprising itaconic amide acid with acrylic acid or acrylamide, which contain carboxylic acid and amide groups capable of coordinating to the copper catalyst, were synthesized by radical polymerization using an azobisisobutyronitrile initiator. These polymers were used as polymer ligands to prepare copper complexes, which were subsequently analyzed by UV–Vis spectroscopy. The complexes were then used as catalysts for the oxidative polymerization of 2,6-dimethylphenol (DMP) to synthesize poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) under oxygen and in the presence of a surfactant in alkaline water. The polymerization conditions were optimized by varying the amounts of polymer ligands and copper precursors, the concentrations of surfactant and hydrogen chloride, and the temperature, resulting in PPO with a maximum yield of 93%, a number-average molecular weight (M n) of 3700, and a molecular weight distribution (M w/M n) of 2.12. This yield is higher than that previously achieved using arginine ligand in water (72%). Furthermore, the optimum conditions were applied in the copolymerization of DMP and 2-allyl-6-methylphenol to obtain a thermally crosslinkable copolymer in 95% yield (M n = 3000, M w/M n = 2.5). In addition, the catalyst complex of the copper–polymer ligand was recovered and reused after the polymerization of DMP. The catalyst maintained its activity even after being recycled five times, without the addition of copper precursor or polymer ligand, thereby demonstrating an environmentally friendly process wherein environmental emissions and production costs can be substantially reduced.