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Chiral metal-organic frameworks have attracted interest for enantioselective separations and catalysis because of their high crystallinity and pores with tunable shapes, sizes, and chemical environments. Chiral frameworks of the type M(dobpdc) (M = Mg, Mn, Fe, Co, Ni, Zn; dobpdc = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) seem particularly promising for potential applications because of their excellent stability, high internal surface areas, and strongly polarizing open metal coordination sites within the channels, but to date these materials have been isolated only in racemic form. Here, we demonstrate that when appended with the chiral diamine trans-1,2-diaminocyclohexane (dach), Mg(dobpdc) adsorbs carbon dioxide cooperatively to form ammonium carbamate chains, and the thermodynamics of CO capture are strongly influenced by enantioselective interactions within the chiral pores of the framework. We further show that it is possible to access both enantiomers of Mg(dobpdc) with high enantiopurity (≥90%) via framework synthesis in the presence of varying quantities of d-panthenol, an inexpensive chiral induction agent. Investigation of dach-M(dobpdc) samples following CO adsorption-using single-crystal and powder X-ray diffraction, solid-state nuclear magnetic resonance spectroscopy, and density functional theory calculations-revealed that the ammonium carbamate chains interact extensively with each other and with the chiral M(dobpdc) pore walls. Subtle differences in the non-covalent interactions accessible in each diastereomeric phase dramatically impact the thermodynamics of CO adsorption.

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All‐optical modulators, where one light modulates the parameters of another light (intensity, phase, frequency, etc.) without external electronic control, have drawn extraordinary attention in all‐optical information processing. In this contribution, by taking advantage of the two‐pass structure of Michelson interferometer and the strong photothermal conversion efficiency of MXene nanomaterials, an all‐optical modulator is demonstrated with a modulation depth of >27 dB, a free spectrum range of 16.8 nm and a pump‐induced phase shift slope of 0.043 π mW−1. Moreover, the all‐optical modulator is successfully employed to switch on/off the intensity of the signal light and load information from one channel to another with comparable response time and baudrate. It is believed that the MXene‐based all‐optical modulator will open a door to practical applications of 2D materials‐based all‐optical devices in all‐optical signal processing.

Single frequency fiber lasers have attracted intense attention in the high precision measure, optical communication and Raman spectroscopy due to their special features including narrow spectral linewidth, low-intensity noise and fiber compatibility [1][2][3][4][5]. Tunable fiber lasers with broad wavelength-sweeping range or fast wavelength-sweeping speed have become key components in dense wavelength division multiplexing (DWDM) transmission systems or high-resolution spectroscopy. Various optical components can achieve wavelength tuning in the field of fiber laser including an acoustic-optic filter [6,7], an electro-optic filter [8], or a fiber Bragg grating filter [9]. However, these devices are usually high-cost and complicated, and needs expensive electronic drivers. Especially, these components cannot be compatible with an all-optical communication system to achieve all-optical wavelength conversion and optical cross-connect. Recently, two-dimensional (2D) material-based all-optical devices have been reported and achieved all-optical modulation and switcher, all-optical actively Q-switching, all-optical thresholding, all-optical wavelength conversion and all-optical information loading [10][11][12][13][14][15][16]. Zhang et al. [17] reported that an all-optical wavelength tuner with a wavelength tuning range of 1.6 nm and a 3-dB spectral width of 0.05 nm was realized when the all-optical modulator (AOM) was inserted into a fiber laser. However, the wavelength tuning range is still very narrow, limiting its practical application in many fields, such as optical communication and spectroscopy. Exploring novel optical structure and optical materials are effective ways to achieve high-performance all-optical wavelength tuning.MXenes, graphene-like 2D materials, have attracted increasing attention as an emerging class of 2D materials due to their outstanding merits including ultrafast optical response, broadband optical absorption and tunable optoelectrical properties, which have exhibited development potential in the fields of the energy storage system, water purification, sensors and electronic devices [18][19][20][21][22][23]. The general formula is M n+1 X n T x (n=1, 2 or 3), where M and T are transition metal and surface terminations, and X is carbon and/or nitrogen [24]. So far, more than 30 types of MXenes have been produced experimentally such as Ti 3 C 2 , Ti 2 C, Nb 2 C and V 2 C [25,26]. In contrast to carbide-based MXenes, nitride-based MXenes exhibit higher electronic conductivity and stability under ambient conditions [27,28]. However, the fabrication of nitride-based MXenes remains challenging due to the intricacy in synthesis and low stability in etchants [29]. In 2016, Urbankowski et al. [29], for the first time, synthesized nitride-based MXenes (Ti 4 N 3 T x ) by heating Ti 4 AlN 3 in a molten fluoride salt. Ti 4 N 3 has a higher density of states than Ti 3 C 2 according to the computation. Surface-enhanced Raman scattering activity of the synthesized Ti 2 NT x achieved a Raman enhancement fac...