A Robust, Porous and Solution-Processable Molecular Crystal Containing Multiple Donor-Acceptor Units

2019 ◽  
Author(s):  
Shengxian Cheng ◽  
Xiaoxia Ma, ◽  
Yonghe He ◽  
Jun He ◽  
Matthias Zeller ◽  
...  
Keyword(s):  
Molecular Crystal ◽  
Bulk Sample ◽  
Intermolecular Forces ◽  
Close Packing ◽  
Molecular Solids ◽  
Molecular Scaffold ◽  
Excellent Thermal Stability ◽  
Crystalline Order ◽  
Donor Acceptor ◽  
Open Packing

We report a curious porous molecular crystal that is devoid of the common traits of related systems. Namely, the molecule does not rely on directional hydrogen bonds to enforce open packing; and it offers neither large concave faces (i.e., high internal free volume) to frustrate close packing, nor any inherently built-in cavity like in the class of organic cages. Instead, the permanent porosity (as unveiled by the X-ray crystal structure and CO<sub>2</sub> sorption studies) arises from the strong push-pull units built into a Sierpinski-like molecule that features four symmetrically backfolded (<b>SBF</b>) side arms. Each side arm consists of the 1,1,4,4-tetracyanobuta-1,3-diene acceptor (TCBD) coupled with the dimethylaminophenyl donor, which is conveniently installed by a cycloaddition-retroelectrocyclization (CA-RE) reaction. Unlike the poor/fragile crystalline order of many porous molecular solids, the molecule here readily crystallizes and the crystalline phase can be easily deposited into thin films from solutions. Moreover, both the bulk sample and thin film exhibit excellent thermal stability with the porous crystalline order maintained even at 200 °C. The intermolecular forces underlying this robust porous molecular crystal likely include the strong dipole interactions and the multiple C···N and C···O short contacts afforded by the strongly donating and accepting groups integrated within the rigid molecular scaffold.

A Robust, Porous and Solution-Processable Molecular Crystal Containing Multiple Donor-Acceptor Units

2019 ◽  
Author(s):  
Shengxian Cheng ◽  
Xiaoxia Ma, ◽  
Yonghe He ◽  
Jun He ◽  
Matthias Zeller ◽  
...  
Keyword(s):  
Molecular Crystal ◽  
Bulk Sample ◽  
Intermolecular Forces ◽  
Close Packing ◽  
Molecular Solids ◽  
Molecular Scaffold ◽  
Excellent Thermal Stability ◽  
Crystalline Order ◽  
Donor Acceptor ◽  
Open Packing

We report a curious porous molecular crystal that is devoid of the common traits of related systems. Namely, the molecule does not rely on directional hydrogen bonds to enforce open packing; and it offers neither large concave faces (i.e., high internal free volume) to frustrate close packing, nor any inherently built-in cavity like in the class of organic cages. Instead, the permanent porosity (as unveiled by the X-ray crystal structure and CO<sub>2</sub> sorption studies) arises from the strong push-pull units built into a Sierpinski-like molecule that features four symmetrically backfolded (<b>SBF</b>) side arms. Each side arm consists of the 1,1,4,4-tetracyanobuta-1,3-diene acceptor (TCBD) coupled with the dimethylaminophenyl donor, which is conveniently installed by a cycloaddition-retroelectrocyclization (CA-RE) reaction. Unlike the poor/fragile crystalline order of many porous molecular solids, the molecule here readily crystallizes and the crystalline phase can be easily deposited into thin films from solutions. Moreover, both the bulk sample and thin film exhibit excellent thermal stability with the porous crystalline order maintained even at 200 °C. The intermolecular forces underlying this robust porous molecular crystal likely include the strong dipole interactions and the multiple C···N and C···O short contacts afforded by the strongly donating and accepting groups integrated within the rigid molecular scaffold.

Cyclotetrabenzoin Acetate: A Macrocyclic Porous Molecular Crystal for CO2 Separations by Pressure Swing Adsorption

2021 ◽  
Author(s):  
Yao-Ting Wang ◽  
Corie M. McHale ◽  
Xiqu Wang ◽  
Chung-Kai Chang ◽  
Yu-Chun Chuang ◽  
...  
Keyword(s):  
Molecular Crystal ◽  
Pressure Swing Adsorption ◽  
Gas Adsorption ◽  
Close Packing ◽  
Separation Performance ◽  
Mixed Gas ◽  
Water Tolerance ◽  
Pressure Swing ◽  
Breakthrough Experiments ◽  
Group Play

A porous molecular crystal (PMC) assembled by close-packing of macrocyclic cyclotetrabenzoin acetate is an efficient adsorbent for selective CO<sub>2</sub> capture. The 7.1´7.1 Å square pore of PMC and its ester C=O group play important roles in improving its affinity for CO<sub>2</sub> molecules. Thermodynamically, the benzene walls of macrocycle strongly promote CO<sub>2</sub> adsorption via [p···p] interactions at low pressure. In addition, the polar carbonyl groups pointing inward the square channels reduce the size of aperture to a 5.0´5.0 Å square, which offers kinetic selectivity for CO<sub>2</sub> capture. The PMC features water tolerance and high structural stability under vacuum and various gas adsorption conditions, which are rare among intrinsically porous organic molecules. In mixed-gas breakthrough experiments, it exhibits efficient CO<sub>2</sub>/N<sub>2</sub> and CO<sub>2</sub>/CH<sub>4</sub> separations under kinetic flow conditions. Most importantly, the moderate adsorbate–adsorbent interaction allows the PMC to be readily regenerated, and therefore applied to pressure swing adsorption (PSA) processes. The eluted N<sub>2</sub> and CH<sub>4</sub> are obtained with over 99.9% and 99.8% purity, respectively, and the separation performance is stable for 30 cycles. Coupled with its easy synthesis, these properties make cyclotetrabenzoin acetate a promising adsorbent for CO<sub>2</sub> separations from flue and natural gases.

A Porous and Solution-Processable Molecular Crystal Stable at 200 °C: The Surprising Donor–Acceptor Impact

2019 ◽  
Vol 19 (12) ◽  
pp. 7411-7419 ◽  
Author(s):  
Shengxian Cheng ◽  
Xiaoxia Ma ◽  
Yonghe He ◽  
Jun He ◽  
Matthias Zeller ◽  
...  
Keyword(s):  
Molecular Crystal ◽  
Donor Acceptor ◽  
Solution Processable

scholarly journals Charge transfer excitons in a donor–acceptor amphidynamic crystal: the role of dipole orientational order

2020 ◽  
Vol 7 (11) ◽  
pp. 2951-2958
Author(s):  
Joshua W. R. Macdonald ◽  
Giacomo Piana ◽  
Massimiliano Comin ◽  
Elizabeth von Hauff ◽  
Gabriele Kociok-Köhn ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Large Amplitude ◽  
Orientational Order ◽  
Molecular Solids ◽  
Electrical Characteristics ◽  
Large Amplitude Motions ◽  
Donor Acceptor ◽  
Charge Transfer Excitons

Large amplitude motions in molecular solids are responsible for anomalous electrical characteristics in amphidynamic crystals. Here we explore the implications for charge transfer excitons photophysics.

Cyclotetrabenzoin Acetate: A Macrocyclic Porous Molecular Crystal for CO2 Separations by Pressure Swing Adsorption

2021 ◽  
Author(s):  
Yao-Ting Wang ◽  
Corie M. McHale ◽  
Xiqu Wang ◽  
Chung-Kai Chang ◽  
Yu-Chun Chuang ◽  
...  
Keyword(s):  
Molecular Crystal ◽  
Pressure Swing Adsorption ◽  
Gas Adsorption ◽  
Close Packing ◽  
Separation Performance ◽  
Mixed Gas ◽  
Water Tolerance ◽  
Pressure Swing ◽  
Breakthrough Experiments ◽  
Group Play

A porous molecular crystal (PMC) assembled by close-packing of macrocyclic cyclotetrabenzoin acetate is an efficient adsorbent for selective CO<sub>2</sub> capture. The 7.1´7.1 Å square pore of PMC and its ester C=O group play important roles in improving its affinity for CO<sub>2</sub> molecules. Thermodynamically, the benzene walls of macrocycle strongly promote CO<sub>2</sub> adsorption via [p···p] interactions at low pressure. In addition, the polar carbonyl groups pointing inward the square channels reduce the size of aperture to a 5.0´5.0 Å square, which offers kinetic selectivity for CO<sub>2</sub> capture. The PMC features water tolerance and high structural stability under vacuum and various gas adsorption conditions, which are rare among intrinsically porous organic molecules. In mixed-gas breakthrough experiments, it exhibits efficient CO<sub>2</sub>/N<sub>2</sub> and CO<sub>2</sub>/CH<sub>4</sub> separations under kinetic flow conditions. Most importantly, the moderate adsorbate–adsorbent interaction allows the PMC to be readily regenerated, and therefore applied to pressure swing adsorption (PSA) processes. The eluted N<sub>2</sub> and CH<sub>4</sub> are obtained with over 99.9% and 99.8% purity, respectively, and the separation performance is stable for 30 cycles. Coupled with its easy synthesis, these properties make cyclotetrabenzoin acetate a promising adsorbent for CO<sub>2</sub> separations from flue and natural gases.

scholarly journals Hydrogen atom disorder in the crystal structure of o-phenylenediacetic acid

2020 ◽  
Vol 19 (1) ◽  
pp. 109-115
Author(s):  
Lenka Krešáková ◽  
Juraj Kuchár ◽  
Juraj Černák
Keyword(s):  
Crystal Structure ◽  
Hydrogen Atom ◽  
Hydrogen Bonds ◽  
Single Crystals ◽  
Powder Diffraction ◽  
Molecular Crystal ◽  
Free Acid ◽  
Bulk Sample ◽  
Hydrogen Atoms ◽  
Carboxylate Groups

H2opda (1) (o-phenylenediacetic acid) was prepared in the form of single crystals. It exhibits molecular crystal structure. The main feature of the supramolecular structure of 1 is formation of hydrogen bonded dimers via a pair of O-H×××O hydrogen bonds. The hydrogen atoms in COOH groups are disordered in 0.67(2):0.33(2) ratio. The conformation of the free acid is characterized by cis arrangement of the carboxylate groups with respect to the plane of the aromatic ring. The powder diffraction pattern of the bulk sample corroborated the phase identity of the commercial material with that of the studied single crystal.

The Structure of Liquids

2004 ◽  
Author(s):  
W. Ronald Fawcett
Keyword(s):  
Molecular Crystal ◽  
Intermolecular Forces ◽  
Ideal Gas ◽  
Fixed Number ◽  
Reference Molecule ◽  
Dilute Gas ◽  
Ion Interactions ◽  
Mechanical Models ◽  
Statistical Mechanical ◽  
Gas Molecules

It is well known from studies of the properties of matter that the liquid state is much more complex than either the gaseous or solid states. Studies of the properties of gases quickly lead to the ideal gas law, which describes the properties of real gases at low pressures and high temperatures. This success is clearly due to the fact that the molecules in a dilute gas are far from one another so that the effects of intermolecular forces and of the finite volume occupied by the gas molecules are negligible. As the pressure of a gas is increased and its temperature lowered, the effects of non-ideality become apparent, and the equation of state becomes more complex. These changes are those required to convert the gas to a liquid. As the molecules come closer together, the influence of intermolecular forces becomes greater and the free volume available for the gas molecules is significantly reduced because of the space occupied by the molecules themselves. The statistical mechanical description of a gas relies upon the concept that the molecules are in constant movement with trajectories determined by collisions with the walls of the container and with other molecules. The probability of finding another molecule in the immediate vicinity of a given molecule is extremely low and does not vary significantly with distance from the reference molecule. On the other hand, solids are characterized by a very ordered structure in which each ion or molecule is surrounded by a fixed number of neighbors whose nature and orientation are determined by the interparticle forces in the crystal. These may be chiefly ion–ion interactions, as in an ionic crystal, or intermolecular forces, as in a molecular crystal. Because of the high state of order in crystals it is a reasonably straightforward problem to calculate their thermodynamic properties on the basis of quite simple statistical mechanical models. One way of conceptualizing a liquid is as a very disordered solid. If one disrupts the structure of the nearest neighbors around a reference molecule in a molecular crystal, the effect of the disruption extends quite far.

scholarly journals Optical, Electrochemical, Thermal, and Structural Properties of Synthesized Fluorene/Dibenzosilole-Benzothiadiazole Dicarboxylic Imide Alternating Organic Copolymers for Photovoltaic Applications

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1147 ◽  
Author(s):  
Ary R. Murad ◽  
A. Iraqi ◽  
Shujahadeen B. Aziz ◽  
Sozan N. Abdullah ◽  
Rebar T. Abdulwahid ◽  
...  
Keyword(s):  
Structural Properties ◽  
Energy Levels ◽  
Average Molecular Weight ◽  
Excellent Thermal Stability ◽  
Alkyl Chains ◽  
Molecular Weights ◽  
Photovoltaic Applications ◽  
Amorphous Nature ◽  
Donor Acceptor ◽  
The Impact

In this work, four donor–acceptor copolymers, PFDTBTDI-DMO, PFDTBTDI-8, PDBSDTBTDI-DMO, and PDBSDTBTDI-8, based on alternating 2,7-fluorene or 2,7-dibenzosilole flanked by thienyl units, as electron-donor moieties and benzothiadiazole dicarboxylic imide (BTDI) as electron-accepting units, have been designed and synthesized for photovoltaic applications. All polymers were synthesized in good yields via Suzuki polymerization. The impact of attaching two different alkyl chains (3,7-dimethyloctyl vs. n-octyl) to the BTDI units upon the solubilities, molecular weights, optical and electrochemical properties, and thermal and structural properties of the resulting polymers was investigated. PFDTBTDI-8 has the highest number average molecular weight (Mn = 24,900 g·mol−1) among all polymers prepared. Dibenzosilole-based polymers have slightly lower optical band gaps relative to their fluorene-based analogues. All polymers displayed deep-lying HOMO levels. Their HOMO energy levels are unaffected by the nature of either the alkyl substituents or the donor moieties. Similarly, the LUMO levels are almost identical for all polymers. All polymers exhibit excellent thermal stability with Td exceeding 350 °C. X-ray powder diffraction (XRD) studies have shown that all polymers have an amorphous nature in the solid state.

The theory of diffuse scattering of X-rays by a molecular crystal

1964 ◽  
Vol 280 (1380) ◽  
pp. 1-22 ◽  
Keyword(s):  
Molecular Crystal ◽  
Diffuse Scattering ◽  
Intermolecular Forces ◽  
X Rays ◽  
Frequency Distributions ◽  
Thermal Diffuse Scattering ◽  
X Ray ◽  
X Ray Scattering ◽  
Modes Of Vibration ◽  
Thermal Diffuse

The theory of diffuse X-ray scattering by a molecular crystal is given, it being stressed that the modes of vibration causing scattering are in general mixed translational and librational. The theory is applied to an idealized model of hexamethylenetetramine, making use of the elastic constants and the Raman frequency to determine some of the molecular interaction constants. Dispersion curves are calculated from which frequency distributions are obtained. These compare well with experimental data. The thermal diffuse scattering is calculated and compared with experiment, and with the predictions of more approximate theories. The similarity between all of these suggests that very careful measurement of X-ray intensities will be necessary before conclusions can be drawn about intermolecular forces in crystals.

Sign in / Sign up

Export Citation Format

Share Document