Host–Guest Molecular Crystals of Diamino-4,4-bithiazole and Dynamic Molecular Motions via Guest Sorption

Abstract

Diamino-4,4-bithiazole (1) formed host–guest binary molecular crystals with various types of organic guest molecules including pyridine (Py), benzonitrile (PhCN), piperidine (Pipe), DMF, THF, 1,4-dioxane (Diox), CH3OH, aniline (Ani), coumarin (Coum), nitrobenzene (PhNO2), hexamethylenetetramine (HMTA), and quinoline (Quino). Single crystal X-ray structural analyses at 100 K revealed the formation of 1·(guest) or 1·(guest)2 crystals. Reversible molecular adsorption–desorption responses were observed with Py, PhCN, Pipe, DMF, and Diox around room temperature as the crystalline powders were heated during the desorption process and exposed to guest vapor during the readsorption process. The adsorption–desorption isotherms of crystalline powders 1 with Diox at 298 K indicated a reversible gate-opening adsorption–desorption process. Although the host–guest molecular crystals 1·(THF)2 and 1·(CH3OH)2 were confirmed by X-ray crystal structural analyses at 100 K, the THF and CH3OH guests were already eliminated at room temperature. Guest desorption processes of crystalline powders 1·(guest) x were not observed in the host–guest molecular crystals with Ani, Coum, PhNO2, HMTA, and Quino after the crystalline powders were heated. A balance of both the dipole moment and vapor pressure of the guest molecules played an essential role to elicit reversible guest sorption. The crystal structures formed on account of double N–H···N hydrogen-bonded one-dimensional (1D) chains between the −NH2 group and the ring nitrogen atom of 1, which interacted to form two-dimensional (2D) sheet structures through π-stacking and/or S···S interactions. Alternating layers of N–H···N hydrogen-bonded herringbone packing of 1 and the guest molecules led to the formation of other types of crystal lattices. The hydrogen-bonding molecular assemblies of 1 demonstrated lattice flexibly via the configuration change in the molecular arrangements according to the boiling point of the guest molecules.

Static Modulation Wave of Arrays of Halogen Interactions Transduced to a Hierarchy of Nanoscale Change Stimuli of Crystalline Rotors Dynamics

“…1 Understanding such events is important in the realms of materials chemistry and physics of molecular machines because the development of elaborate sensory devices with increasing levels of complexity is also required to accurately report changes that occur in the environment of their dynamic components. [2][3][4][5][6][8][9][10] Here we present a study where what can be seen as a static modulation wave across parallel arrays [7,8] of interacting iodine atoms in crystalline 1,4-Bis((4'-(iodoethynyl)phenyl)ethynyl) bicyclo [2.2.2]octane rotors, 1 (Figure 1) changes the structure from one-half molecule to three-and-a-half molecules in the asymmetric unit below a phase transition at 105 K. The remarkable finding is that the complex, total 1 H spinlattice relaxation rate, T1 -1 , revealed by variable-temperature, variable-field experiments, is the weighted sum of the relaxation rates of the four contributing rotors relaxation rates. Hence, magnetic relaxation transforms from a process determined by a single molecular rotator in the high temperature phase into one that has distinguishable weighted contribution from the four new sites, each with distinguishable exchange frequencies reflecting Arrhenius parameters with different activation barriers (Ea) and attempt frequencies (τo -1 ).…”

“…In addition to drawing attention to the susceptibility of extended, non-covalent halogen-bond arrays to undergo concerted modulation in their temperature phase diagrams, [8a,b] the results observed with compound 1 provide [8a,b,9,10] the kind of in-depth insight on the mechanism of motion required on the way towards a control of molecular machines at the nanoscale. [2][3][4][5][6] Supporting Information Supporting Figures and Tables, Synthesis, Crystal structures at 120 K and 90 K, VT 1 H spinlattice relaxation time: basic principles and experimental details, computational details. CCDC 1577087 and 1577088 contain the crystallographic data for this paper.…”

Reversible Channel–Layer Structural Transformation of a Hydrogen-Bonded Bis-Urea Macrocycle

“…One-dimensional (1D) tubular channels have been utilized for ion and molecular transport, where coupled Na + -K + ionic transport has been observed in biological molecular assemblies. − Because the 1D transport system has both directionality and anisotropy, artificial ionic channels have attracted much attention for the fabrication of passive and gated ionic transport systems. − A large number of synthetic approaches have been reported for the fabrication of artificial 1D channels based on amphiphilic, polymeric, and macrocyclic molecules with hydrogen bonding and van der Waals interactions. − Simple and well-known low-molecular-weight van der Waals crystals of tris­( o -phenylenedioxy)­cyclotriphosphazene (TPP) derivatives have been reported to form 1D channels, where weak van der Waals interactions form 1D channels in the close-packing crystal structure. − Because the energies of van der Waals interactions are quite low, around 1–2 kJ mol –1 , van der Waals molecular assemblies are easily dissociated by external stimuli such as heat and ultrasonic energy . In contrast, hydrogen bonds have energies ranging from 5 to 20 kJ mol –1 , allowing controlled association–dissociation processes of molecular assemblies using external stimuli. − For example, hydrogen bonds in complementary base pairs in DNA and the secondary structures of proteins play an important role in the fabrication of biological molecular assemblies, and controllable hydrogen-bonding interactions have been utilized for repair and reconstruction of molecular assembly structures. − …”

“…The magnitude of hydrogen-bonding interaction energies is suitable for a reversible structural transformation driven by external factors such as temperature, pressure, and molecular adsorption. − Although hydrogen-bonded host–guest complexes of 1 with AcOH have been identified in the 1D channel, other guest molecules with a variety of sizes, shapes, and intermolecular interactions have not been examined from the viewpoint of the structural diversity for hydrogen-bonding network structures. Herein, we tried to fabricate the 1 ·(guest) complexes with various guest molecules: dichloroacetic acid (Cl 2 AcOH), pyrrole (Pyrr), pyridine (Py), and 3,4-difluoroaniline (F 2 Ani), 1,2-diaminoethane (EDA), 1,3-diaminopropane (ProDA), 1,5-diaminopentane (PenDA), and 1,7-diaminoheptane (HepDA) (Scheme ).…”

Arylene Ethynylene-Functionalized Bithiazole-Based Zinc Polymers for Ultraefficient Photocatalytic Activity

“…24,25 In addition, bithiazole (BTz)-bridged polymer receives a great deal of uses, including benzothiadiazole moiety, especially for PHP. 26−28 Thus, the incorporation of CPs into BTz, and the corresponding polymers were systematically characterized (Scheme 1). 29−34 Moreover, these samples were investigated for photocatalytic activity under visible light.…”