Polymer Solutions in Microflows: Tracking and Control over Size Distribution.

Microfluidics provides cutting-edge technological advancements for the in-channel manipulation and analysis of dissolved macromolecular species. The intrinsic potential of microfluidic devices to control key characteristics of polymer macromolecules such as their size distribution requires unleashing its full capacity. This work proposes a combined approach to analyzing the microscale behavior of polymer solutions and modifying their properties.

An Ultramicroporous Physisorbent Sustained by a Trifecta of Directional Supramolecular Interactions.

2D and 3D porous coordination networks (PCNs) as exemplified by metal-organic frameworks, MOFs, have garnered interest for their potential utility as sorbents for molecular separations and storage. The inherent modularity of PCNs has enabled the development of crystal engineering strategies for systematic fine-tuning of pore size and chemistry in families of related PCNs. The same cannot be said about one-dimensional (1D) coordination polymers, CPs, which are understudied with respect to porosity.

Crystal engineering of a new platform of hybrid ultramicroporous materials and their CH/CO separation properties.

Hybrid ultramicroporous materials (HUMs) comprised of combinations of organic and inorganic linker ligands are a leading class of physisorbents for trace separations involving C1, C2 and C3 gases. First generation HUMs are modular in nature since they can be self-assembled from transition metal cations, ditopic linkers and inorganic "pillars", as exemplified by the prototypal variant, SIFSIX-3-Zn (3 = pyrazine, SIFSIX = SiF ). Conversely, HUMs that utilise chelating ligands such as ethylenediamine derivatives are yet to be explored as sorbents.

Modulation of Water Vapor Sorption by Pore Engineering in Isostructural Square Lattice Topology Coordination Networks.

We report a crystal-engineering study conducted upon a platform of three mixed-linker square lattice () coordination networks of general formula [Zn(Ria)(bphy)] [bphy = 1,2-bis(pyridin-4-yl)hydrazine, HRia = 5-position-substituted isophthalic acid, and R = -Br, -NO, and -OH; compounds -]. Analysis of single-crystal X-ray diffraction data of - and the simulated crystal structure of revealed that - are isomorphous and sustained by bilayers of networks linked by hydrogen bonds. Although similar pore shapes and sizes exist in -, distinct isotherm shapes (linear and S shape) and uptakes (2.

Molecular Orientation Behavior of Lyotropic Liquid Crystal-Carbon Dot Hybrids in Microfluidic Confinement.

Lyotropic liquid crystals represent an important class of anisotropic colloid systems. Their integration with optically active nanoparticles can provide us with responsive luminescent media that offer new fundamental and applied solutions for biomedicine. This paper analyzes the molecular-level behavior of such composites represented by tetraethylene glycol monododecyl ether and nanoscale carbon dots in microfluidic channels.

Effect of Polymorphism on the Sorption Properties of a Flexible Square-Lattice Topology Coordination Network.

The stimulus-responsive behavior of coordination networks (CNs), which switch between closed (nonporous) and open (porous) phases, is of interest because of its potential utility in gas storage and separation. Herein, we report two polymorphs of a new square-lattice () topology CN, , of formula [Cu(Imibz)] (HImibz = {[4-(1-imidazol-1-yl)phenylimino]methyl}benzoic acid), isolated from the as-synthesized CN , which subsequently transformed to a narrow pore solvate, , upon mild activation (drying in air or heating at 333 K under nitrogen). contains MeOH in cavities, which was removed through exposure to vacuum for 2 h, yielding the nonporous (closed) phase .

Dinuclear Copper Sulfate-Based Square Lattice Topology Network with High Alkyne Selectivity.

Porous coordination networks (PCNs) sustained by inorganic anions that serve as linker ligands can offer high selectivity toward specific gases or vapors in gas mixtures. Such inorganic anions are best exemplified by electron-rich fluorinated anions, e.g.

Switching Adsorbent Layered Material that Enables Stepwise Capture of C Aromatics via Single-Crystal-to-Single-Crystal Transformations.

Separation of the C aromatic isomers, xylenes (PX, MX, and OX) and ethylbenzene (EB), is important to the petrochemical industry. Whereas physisorptive separation is an energy-efficient alternative to current processes, such as distillation, physisorbents do not generally exhibit strong C selectivity. Herein, we report the mixed-linker square lattice () coordination network [Zn(sba)(bis)]·DMF (, Hsba or = 4,4'-sulfonyldibenzoic acid, bis or = trans-4,4'-bis(1-imidazolyl)stilbene) and its C sorption properties.

Effect of Extra-Framework Anion Substitution on the Properties of a Chiral Crystalline Sponge.

Chiral metal-organic materials, CMOMs, are of interest as they can offer selective binding sites for chiral guests. Such binding sites can enable CMOMs to serve as chiral crystalline sponges (CCSs) to determine molecular structure and/or purify enantiomers. We recently reported on the chiral recognition properties of a homochiral cationic diamondoid, dia, network {[Ni(-IDEC)(bipy)(HO)][NO]} (-IDEC = -indoline-2-carboxylicate, bipy = 4,4'-bipyridine), .

Water vapour induced structural flexibility in a square lattice coordination network.

Herein, we introduce a new square lattice topology coordination network, sql-(1,3-bib)(ndc)-Ni, with three types of connection and detail its gas and vapour induced phase transformations. Exposure to humidity resulted in an S-shaped isotherm profile, suggesting potential utility of such materials as desiccants.

Tuning Molecular Orientation Responses of Microfluidic Liquid Crystal Dispersions to Colloid and Polymer Flows.

An important approach to molecular diagnostics is integrating organized substances that provide complex molecular level responses to introduced chemical and biological agents with conditions that optimize and distinguish such responses. In this respect, liquid crystal dispersions are attractive components of molecular diagnostic tools. This paper analyzes a colloid system, containing a nematic liquid crystal as a dispersed phase, and aqueous surfactant and polymer solutions as the continuous phases.

Supramolecular isomerism and structural flexibility in coordination networks sustained by cadmium rod building blocks.

Bifunctional N-donor carboxylate linkers generally afford and topology coordination networks of general formula ML that are based upon the MN(CO) molecular building block (MBB). Herein, we report on a new N-donor carboxylate linker, β-(3,4-pyridinedicarboximido)propionate (PyImPr), which afforded Cd(PyImPr) reaction of PyImPrH with Cd(acetate)·2HO. We observed that, depending upon whether Cd(PyImPr) was prepared by layering or solvothermal methods, 2D or 3D supramolecular isomers, respectively, of Cd(PyImPr) were isolated.

Crystal Engineering of a Chiral Crystalline Sponge That Enables Absolute Structure Determination and Enantiomeric Separation.

Chiral metal-organic materials (CMOMs), can offer molecular binding sites that mimic the enantioselectivity exhibited by biomolecules and are amenable to systematic fine-tuning of structure and properties. Herein, we report that the reaction of Ni(NO), -indoline-2-carboxylic acid (-IDECH), and 4,4'-bipyridine (bipy) afforded a homochiral cationic diamondoid, , network, [Ni(-IDEC)(bipy)(HO)][NO], . Composed of rod building blocks (RBBs) cross-linked by bipy linkers, the activated form of adapted its pore structure to bind four guest molecules, 1-phenyl-1-butanol (1P1B), 4-phenyl-2-butanol (4P2B), 1-(4-methoxyphenyl)ethanol (MPE), and methyl mandelate (MM), making it an example of a chiral crystalline sponge (CCS).

Dynamic Flow Control over Optical Properties of Liquid Crystal-Quantum Dot Hybrids in Microfluidic Devices.

In this paper, we report developing approaches to tuning the optical behavior of microfluidic devices by infusing smart hybrids of liquid crystal and quantum dots into microchannel confinement. We characterize the optical responses of liquid crystal-quantum dot composites to polarized and UV light in single-phase microflows. In the range of flow velocities up to 10 mm/s, the flow modes of microfluidic devices were found to correlate with the orientation of liquid crystals, dispersion of quantum dots in homogeneous microflows and the resulting luminescence response of these dynamic systems to UV excitation.

Control over Phase Transformations in a Family of Flexible Double Diamondoid Coordination Networks through Linker Ligand Substitution.

In this work, we present the first metal-organic framework (MOF) platform with a self-penetrated double diamondoid () topology that exhibits switching between closed (nonporous) and open (porous) phases induced by exposure to gases. A crystal engineering strategy, linker ligand substitution, was used to control gas sorption properties for CO and C3 gases. Specifically, bimbz (1,4-bis(imidazol-1-yl)benzene) in the coordination network ([Ni(bimbz)(bdc)(HO)], Hbdc = 1,4-benzenedicarboxylic acid) was replaced by bimpz (3,6-bis(imidazol-1-yl)pyridazine) in ([Ni(bimpz)(bdc)(HO)]).

One Atom Can Make All the Difference: Gas-Induced Phase Transformations in Bisimidazole-Linked Diamondoid Coordination Networks.

Coordination networks (CNs) that undergo gas-induced transformation from closed (nonporous) to open (porous) structures are of potential utility in gas storage applications, but their development is hindered by limited control over their switching mechanisms and pressures. In this work, we report two CNs, [Co(bimpy)(bdc)] () and [Co(bimbz)(bdc)] () (Hbdc = 1,4-benzendicarboxylic acid; bimpy = 2,5-bis(1H-imidazole-1-yl)pyridine; bimbz = 1,4-bis(1H-imidazole-1-yl)benzene), that both undergo transformation from closed to isostructural open phases involving at least a 27% increase in cell volume. Although and only differ from one another by one atom in their -donor linkers (bimpy = pyridine, and bimbz = benzene), this results in different pore chemistry and switching mechanisms.

Structural Phase Transformations Induced by Guest Molecules in a Nickel-Based 2D Square Lattice Coordination Network.

Herein, we report the crystal structure and guest binding properties of a new two-dimensional (2D) square lattice () topology coordination network, , which is comprised of two linker ligands with diazene (azo) moieties, ()-1,2-di(pyridin-4-yl)diazene(azpy) and ()-5-(phenyldiazenyl)isophthallate(pdia). underwent guest-induced switching between a closed (nonporous) phase and several open (porous) phases, but unlike the clay-like layer expansion to distinct phases previously reported in switching networks, a continuum of phases was formed. In effect, exhibited elastic-like properties induced by adaptive guest binding.

Tuning Properties of Polyelectrolyte-Surfactant Associates in Two-Phase Microfluidic Flows.

This work focuses on identifying and prioritizing factors that allow control of the properties of polyelectrolyte-surfactant complexes in two-phase microfluidic confinement and provide advantages over synthesis of such complexes in macroscopic conditions. We characterize the impact of polymer and surfactant aqueous flow conditions on the formation of microscale droplets and fluid threads in the presence of an immiscible organic solvent. We perform an experimental and selected numerical analysis of fast supramolecular reactions in droplets and threads.

A Robust Molecular Porous Material for C H /CO Separation.

A molecular porous material, MPM-2, comprised of cationic [Ni (AlF )(pzH) (H O) ] and anionic [Ni Al F (pzH) (H O) ] complexes that generate a charge-assisted hydrogen-bonded network with pcu topology is reported. The packing in MPM-2 is sustained by multiple interionic hydrogen bonding interactions that afford ultramicroporous channels between dense layers of anionic units. MPM-2 is found to exhibit excellent stability in water (>1 year).

Activation and Switching of Supramolecular Chemical Signals in Multi-Output Microfluidic Devices.

In this study, we report on the developing of a continuous microfluidic reaction device that allows selective activation of polyelectrolyte-surfactant chemical signals in microflows and switches them between multiple outputs. A numerical model was developed for convection-diffusion reaction processes in reactive polymer-colloid microfluidic flows. Matlab scripts and scaling laws were developed for this model to predict reaction initiation and completion conditions in microfluidic devices and the location of the reaction front.