Highly selective CO2 sorption and inverse CO2/C2H2 sorption selectivity (4.8 at 278 K, 100 kPa) were achieved with an organic–inorganic ionic crystal. The key for the high affinity toward CO2 is the combination of structural flexibility and strong binding sites (K+) characteristic of organic–inorganic ionic crystals.

Mating drive is balanced by a need to safeguard resources for offspring, yet the neural basis for negative regulation of mating remains poorly understood. In rodents, pheromones critically regulate sexual behavior. Here, we observe suppression of adult female sexual behavior in mice by exocrine gland-secreting peptide 22 (ESP22), a lacrimal protein from juvenile mice. ESP22 activates a dedicated vomeronasal receptor, V2Rp4, and V2Rp4 knockout eliminates ESP22 effects on sexual behavior. Genetic tracing of ESP22-responsive neural circuits reveals a critical limbic system connection that inhibits reproductive behavior. Furthermore, V2Rp4 counteracts a highly related vomeronasal receptor, V2Rp5, that detects the male sex pheromone ESP1. Interestingly, V2Rp4 and V2Rp5 are encoded by adjacent genes, yet couple to distinct circuits and mediate opposing effects on female sexual behavior. Collectively, our study reveals molecular and neural mechanisms underlying pheromone-mediated sexual rejection, and more generally, how inputs are routed through olfactory circuits to evoke specific behaviors.

Proton conduction in alkali metal ion-exchanged porous ionic crystals A[CrO(OOCH)(etpy)][α-SiWO]·nHO [I-A] (A = Li, Na, K, Cs, etpy = 4-ethylpyridine) is investigated. Single crystal and powder X-ray diffraction measurements show that I-A possesses analogous one-dimensional channels where alkali metal ions (A) and water of crystallization exist. Impedance spectroscopy and water diffusion measurements of I-A show that proton conductivities are low (10-10 S cm) under low relative humidity (RH), and protons mostly migrate as HO with HO as vehicles (vehicle mechanism). The proton conductivity of I-A increases with the increase in RH and is largely dependent on the types of alkali metal ions. I-Li shows a high proton conductivity of 1.9 × 10 S cm (323 K) and a low activation energy of 0.23 eV under RH 95%. Under high RH, alkali metal ions with high ionic potentials (e.g., Li) form a dense and extensive hydrogen-bonding network of water molecules with mobile protons at the periphery, which leads to high proton conductivities and low activation energies via rearrangement of the hydrogen-bonding network (Grotthuss mechanism).

Rodents use the vomeronasal olfactory system to acquire both inter- and intra-specific information from the external environment and take appropriate actions. For example, urinary proteins from predator species elicit avoidance in mice, while those from male mice attract female mice. In addition to urinary proteins, recent studies have highlighted the importance of lacrimal proteins for intra-specific communications in mice. However, whether the tear fluid of other species also mediates social signals remains unknown. Here, we show that a lacrimal protein in rats (predators of mice), called cystatin-related protein 1 (ratCRP1), activates the vomeronasal system of mice. This protein is specifically produced by adult male rats in a steroid hormone-dependent manner, activates the vomeronasal system of female rats, and enhances stopping behavior. When detected by mice, ratCRP1 activates the medial hypothalamic defensive circuit, resulting in decreased locomotion coupled with lowered body temperature and heart rate. Notably, ratCRP1 is recognized by multiple murine type 2 vomeronasal receptors, including Vmn2r28. CRISPR/Cas9-mediated deletion of vmn2r28 impaired both ratCRP1-induced neural activation of the hypothalamic center and decrease of locomotor activity in mice. Taken together, these data reveal the neural and molecular basis by which a tear fluid compound in rats affects the behavior of mice. Furthermore, our study reveals a case in which a single compound that mediates an intra-specific signal in a predator species also functions as an inter-specific signal in the prey species.

Ionic crystals [Cr3O(OOCCH2 X)6(H2O)3]4[α-SiW12O40]·14H2O (X = Cl [Ia], Br [IIa]) are synthesized by complexation of halogen-substituted macrocations with a silicododecatungstate. Compounds Ia and IIa possess analogous one-dimensional winding channels, and the channel walls are composed of oxygen atoms of silicododecatungstates and −CH2 X groups of macrocations. Water of crystallization in Ia (IIa) is desorbed by the treatment in vacuo or under a dry N2 or He flow at 298–303 K, and the corresponding guest free phases Ib (IIb) are obtained. Propylene/propane and ethylene/ethane sorption ratios of Ib at 298 K and 100 kPa are 6.1 and 3.6, respectively. The ethylene/ethane sorption ratio of IIb at 298 K and 100 kPa is 2.8. These values are much larger than those of conventional sorbents. In situ 13C MAS NMR spectra of ethylene or ethane sorbed in Ib suggest that host–guest interaction for ethylene is larger than that for ethane. DFT calculation and Monte Carlo simulation are carried out to elucidate the nature of the high ethylene/ethane sorption ratios: The bridging carboxylates (−OOCCH2 X) are polarized by incorporation of highly electronegative halogens. Ethylene resides along the channel wall with the σh plane facing the channel wall, while ethane resides randomly in the channels of Ib and IIb. These results suggest that the olefin sorption is enhanced by electrostatic interaction between the π-electron of olefins and highly polarized halogen-substituted macrocations and/or silicododecatungstates.