No abstract

The regional tectonic stress field, basin development, and crustal deformation of the NE Japan arc in the interval between 32 Ma to the Quaternary can be synthesized based on dike, vein, and fault orientation data, as well as on the compilation of the regional geology. An extensional stress field became prevalent from 32 Ma, and major normal faulting started at 25–20 Ma, which resulted from back arc rifting. Normal faulting, trending nearly parallel to the arc, propagated from the present Japan Sea coast to the forearc side, following the trenchward migration of the main volcanic field. From 20 to 15 Ma, normal faults with an oblique trend to the arc developed due to the counterclockwise rotation of NE Japan. The rapid clockwise rotation of SW Japan since 16 Ma produced a NW‐SE directed transtensional stress regime in the NE Japan arc. Due to crustal stretching associated with this pull‐apart movement, the back arc side of the NE Japan arc subsided rapidly to middle bathyal environments. After the termination of the opening of the Japan Sea at about 14 Ma, a neutral stress regime prevailed, which included phases of both weak extension and compression. Lithospheric cooling eventually led to thermal subsidence of the back arc region, and igneous underplating caused uplift of the axial zone of the volcanic arc. The increase in velocity of the westward motion of the Pacific plate at around 4 Ma produced strong compression across the arc, reactivating most of the Miocene normal faults, and uplifting the volcanic arc. The greatest crustal shortening occurred in areas that were stretched the most in the Miocene within the volcanic arc, which implies tectonic inversion.

Carbon monoxide (CO) produced in many large-scale industrial oxidation processes is difficult to separate from nitrogen (N2), and afterward, CO is further oxidized to carbon dioxide. Here, we report a soft nanoporous crystalline material that selectively adsorbs CO with adaptable pores, and we present crystallographic evidence that CO molecules can coordinate with copper(II) ions. The unprecedented high selectivity was achieved by the synergetic effect of the local interaction between CO and accessible metal sites and a global transformation of the framework. This transformable crystalline material realized the separation of CO from mixtures with N2, a gas that is the most competitive to CO. The dynamic and efficient molecular trapping and releasing system is reminiscent of sophisticated biological systems such as heme proteins.

The development of a new methodology for visualizing and detecting gases is imperative for various applications. Here, we report a novel strategy in which gas molecules are detected by signals from a reporter guest that can read out a host structural transformation. A composite between a flexible porous coordination polymer and fluorescent reporter distyrylbenzene (DSB) selectively adsorbed CO₂ over other atmospheric gases. This adsorption induced a host transformation, which was accompanied by conformational variations of the included DSB. This read-out process resulted in a critical change in DSB fluorescence at a specific threshold pressure. The composite shows different fluorescence responses to CO₂ and acetylene, compounds that have similar physicochemical properties. Our system showed, for the first time, that fluorescent molecules can detect gases without any chemical interaction or energy transfer. The host-guest coupled transformations play a pivotal role in converting the gas adsorption events into detectable output signals.

No abstract

No abstract

The adsorptive separation of C2H2 and CO2 via porous materials is nontrivial due to the close similarities of their boiling points and kinetic diameters. In this work, we describe a new flexible porous coordination polymer (PCP) [Mn(bdc)(dpe)] (H2bdc = 1,4-benzenedicarboxylic acid, dpe = 1,2-di(4-pyridyl)ethylene) having zero-dimensional pores, which shows an adsorbate discriminatory gate effect. The compound shows gate opening type abrupt adsorption for C2H2 but not for CO2, leading to an appreciable selective adsorption of CO2 over C2H2 at near ambient temperature (273 K). The origin of this unique selectivity, as unveiled by in situ adsorption-X-ray diffraction experiments and density functional theory calculations, is due to vastly different orientations between the phenylene ring of bdc and each gas in the nanopores. The structural change by photochemical transformation of this PCP via [2 + 2] photodimerization leads to the removal of inverse CO2/C2H2 selectivity, verifying the mechanism of the guest discriminatory gate effect.

A MIL‐101‐based porous coordination polymer (PCP) containing sulfonic acid groups is synthesized. The sulfonic groups are exposed on the pore surface and act as strong Brønsted acid sites. This solid acid PCP catalytically hydrolyzes cellulose into mono‐ and disaccharides and shows high durability in the catalytic reaction.