Coexistence of Naked-Eye Mechanochromism, Vapochromism, and Thermochromism in a Soft Crystalline Layered Nickel(II) Coordination Polymer

Abstract

Chromic materials have the potential to be used in a variety of applications, including memory devices and sensors. Despite fact that stimuli-responsive chromic materials have been widely reported to date, fabricating chromic materials that can be responsive to multiple external stimuli remains a challenge. Herein, a new multistimuli responsive chromic coordination polymer of {was successfully synthesized. Single-crystal X-ray diffraction analysis revealed that 1 exhibits a soft crystalline 3dimenional (3D) supramolecular framework generated by weakly interlayered stacking interactions between 2D coordination polymers. Compound 1 revealed unprecedented naked-eye mechanochromism, vapochromism, and thermochromism in response to multiple external stimuli including manual grinding, amine and alcohol vapors, and heat, respectively. The chromism related to the structural feature was clarified by SC-XRD, PXRD, TGA, elemental analysis, and spectroscopic techniques.

Simultaneous Occurrence of Vapochromism and Vapoluminescence in Formaldehyde-Responsive Amino-Functionalized Copper(I) Polymorphic Coordination Polymers

“…The coordination of organic ligands and metal ions in CPs results in diverse structures, ranging from one-dimensional (1D) chains to more complicated two-dimensional (2D) layers and three-dimensional (3D) frameworks . Since building blocks in the crystallization conditions can be rationally designed, different crystalline architectures of CPs with the desired properties can be obtained, leading to a potential application of CPs in various areas including adsorption and separation, catalysis, and chemical sensing. − In particular, CPs have been widely applied as chromic materials in response to invisibly toxic volatile organic compounds (VOCs). − CPs undergo a color or luminescent change, exhibiting vapochromism or vapoluminescence, respectively, due to an alteration of their electronic transition energy triggered by interactions with the vapor molecules via two main mechanisms: (i) a modification of the intermolecular noncovalent interactions including metallophilic, π–π, and hydrogen-bonding interactions, − and (ii) a change in the coordination sphere via coordinated substitution. − Although many vapor-responsive CPs have been developed so far, the simultaneous occurrence of vapochromism and vapoluminescence in the vapor-responsive CPs is rarely observed. − …”

Recent progress on MOF-based optical sensors for VOC sensing

“…In another example, Tunsrichon and co-workers introduced a Ni-viologen based 2D MOF {[Ni(pzt) 2 (H 2 O) 2 ](H 2 O)(DMF)} n (Hpzt = 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol) with naked-eye chromism in the presence of primary amines and methanol vapours. 97 Upon exposure to NH 3 , methylamine, ethylamine and ethylenediamine, the intrinsic blue colour changed by replacing coordinated H 2 O molecules with a strong-field amine through forming Ni–N bonds. Bulkier amine vapours did not induce a chromic response due to higher steric hindrance.…”

“…Consequently, the resulting tetrahedral geometry induces a reduction in the d-orbital splitting energy resulting in a redshi in the adsorption spectrum and the colour change of Co 3 [Co(CN) 6 ] 2 . In another example, Tunsrichon and co-workers introduced a Ni-viologen based 2D MOF {[Ni(pzt) 2 (H 2 O) 2 ](H 2 -O)(DMF)} n (Hpzt = 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol) with naked-eye chromism in the presence of primary amines and methanol vapours 97. Upon exposure to NH 3 , methylamine, ethylamine and ethylenediamine, the intrinsic blue colour changed by replacing coordinated H 2 O molecules with a strong-eld amine through forming Ni-N bonds.…”

Solvent-Modulated Self-Assembly of Naphthalenediimide-Based Cd(II) Complexes and the Controllable Photochromism via Conformational Isomerization

“…Since the 21st century, optical information functional materials developed with light as the information carrier and combined with optical technology have shown great application potential in optics and electricity and have contributed to improving the quality of human life. − Among them, photochromic functional materials have piqued the interest of scientists because of their practical application value and potential development space in optics, − magnetism, medicine, catalysis, fluorescence, , and so on. Among various photochromic materials, coordination polymers (CPs) photochromic systems based on electron donor–acceptor (D-A) type photo-induced intermolecular electron transfer (ET) have received a lot of attention due to their exceptional photochromic characteristics, such as instantaneous photoresponse, wide photoresponse range, and intense color rendering contrast. − However, the majority of reported ET photochromic materials have photoresponse ranges that are generally in the UV area or X-ray region for higher energy excitations. − Since UV/X-ray light accounts for only a tiny fraction of the total solar energy, the difficulty of obtaining UV/X-ray light in daily life dramatically limits the application of such photochromic materials . The development and enhancement of photochromic materials with a greater sensitivity to visible light is urgent and hugely challenging. , Visible-light photochromic devices are the solution to this problem, and the key to manufacturing them is expanding exciton absorption to the visible area. , Representative studies have combined visible photochromic agents such as Pt, Au, and CdS nanoparticles with polymetallic oxides or selected inorganic semiconductors with small optical band gaps and significant absorption coefficients as electron donors (EDs), which may result in exciton absorption in the visible region. − Nevertheless, these tactics often result in distinct initial color states that severely affect the occurrence of significant color contrast .…”