Fluorescent probe for imaging intercellular tension: molecular force approach.

Cellular mechanical force plays a crucial role in numerous biological processes, including wound healing, cell development, and metastasis. To enable imaging of intercellular tension, molecular tension probes were designed, which offer a simple and efficient method for preparing Au-DNA intercellular tension probes with universal applicability. The proposed approach utilizes gold nanoparticles linked to DNA hairpins, enabling sensitive visualization of cellular force in vitro. Specifically, the designed Au-DNA intercellular tension probe includes a molecular spring flanked by a fluorophore-quencher pair, which is anchored between cells. As intercellular forces open the hairpin, the fluorophore is de-quenched, allowing for visualization of cellular force. The effectiveness of this approach was demonstrated by imaging the cellular force in living cells using the designed Au-DNA intercellular tension probe.

Molecular dynamics study of lithium intercalation into -OH functionalized carbon nanotube bundle.

The influence of hydroxyl group (-OH) on carbon nanotube (CNT) interacting with lithium (Li) ions has been investigated via ab initio molecular dynamic (MD) simulations. Compared with the pure CNT, a higher efficiency has been observed for lithium intercalating into CNT-OH bundle. At lower Li ion density and CNT bundle density, CNT-OH exhibits higher intercalation efficiency than the pristine and ammonium functionalized CNTs. As the increasing of Li ion densities and CNT bundle densities, Li ions tend to intercalate into the interlayer between CNT-OH tubes instead of the interior of CNT-OH tubes. We also observe the destruction of hydroxyl groups during the intercalation of Li ions into interlayer of CNT-OH bundle. It is therefore suggested that eliminating the intercalation of Li ions into interlayer between tubes is important for the design of Li ion batteries.

Photo-Responsive Micelles with Controllable and Co-Release of Carbon Monoxide, Formaldehyde and Doxorubicin.

Endogenous gases have attracted much attention due to their potent applications in disease therapies. The combined therapy, including gaseous molecules and other medicines that can create synergistic effects, is a new way for future treatment. However, due to the gaseous state, gas utilization in medical service is still limited. To pave the way for future usage, in this work, an amphiphilic block copolymer containing nitrobenzyl ether, 3-hydroxyflavone (3-HF) derivatives and ether linker was constructed. The nitrobenzyl ether group endows the polymer with a photo-responsive character. Upon light illumination, 3-HF derivatives can be triggered for carbon monoxide (CO) release. The ether linker can also be released emitting formaldehyde (FA). The self-assembly induced micelle can encompass medicine, e.g., doxorubicin (DOX), into it and a controlled release of DOX can be realized upon light illumination. As far as we know, there is no report on the combination donor of CO and DOX and this is the first attempt on the co-release of CO, FA and DOX.

A rational design of a cascaded DNA circuit for nanoparticle assembly and its application in the discrimination of single-base changes.

In the field of dynamic DNA nanotechnology, a designable DNA assembly circuit based on the toehold-mediated strand displacement reaction has demonstrated its ability to program the self-assembly of nanoparticles. However, the laborious work for the modification of nanoparticles with oligonucleotides, the long assembly time, and the circuit leakage prevent its further and scalable applications. To this end, cascaded circuits composed of two recycling circles are rationally designed in this study. Through the pre-initiation of the autonomous reaction, nanoparticles as sensing elements and no additionally exposed bases on the substrate hybridized with fuel strand, the real assembly time and signal leakage for diagnostic application can be effectively reduced and eliminated, thus offering a promising methodology for future point-of-care testing.

Origin of heterogeneous dynamics in local molecular structures of ionic liquids.

Room-temperature ionic liquids (ILs) are generally considered as structurally heterogeneous with inherent polar/apolar phase separation. However, even after a decade of research, local dynamics in the heterogeneous structures of ILs remain neglected. Such local dynamics may influence the ion transport of electrolytes, as well as the reaction rate of solvents. In this study, we performed molecular dynamics simulation to analyze the local dynamics for the structural heterogeneity of ILs. Calculations of the diffusion, reorientation, and association dynamics showed a distinct heterogeneous dynamics between the polar and apolar regions of ILs. Further studies demonstrated that such local dynamic differences originate from local structural heterogeneity. Different energy barriers determine a predominant fast reorientation dynamics in apolar regions and a locally vibrating behavior in polar regions. Additionally, we suggested a new jumping mechanism to clarify the dynamic heterogeneity of ions in the polar regions. The results will help determine the origin of the heterogeneous dynamics in IL local structures and provide a theoretical basis for tuning the dynamic properties of ILs used as electrolytes or reaction solvents.

Dilute or Concentrated Electrolyte Solutions? Insight from Ionic Liquid/Water Electrolytes.

When room-temperature ionic liquids (IL) are used as an electrolyte, their transport behaviors are still under heavy debate due to their complicated ion-associations. In this article, we conducted molecular dynamics simulations to study the molecular scale ion associations from the very dilute 1-butyl-3-methylimidazolium iodide/water solution to the pure IL. It revealed that ions are localized in a multicoordinated ion cage structure with nanoseconds in concentrated IL solutions. Dynamics analyses indicate that the transport of this solution can be depicted by the Debye-Hückel model only in dilute IL/water electrolyte. The velocity and rotational correlation functions showed that the lifetime of translational and rotational motions are at the level of picoseconds and nanoseconds, respectively, because of the ion cage effect. The lifetime of ion association demonstrated that the recombination of association ions was prevalent in IL solutions. It means that the dipolar or stable contact ion-pairs model may not be suitable for depicting the IL transport.

Chemiluminescence behavior of CdTe-hydrogen peroxide enhanced by sodium hypochlorite and sensitized sensing of estrogens.

It has been found that sodium hypochlorite enhanced the chemiluminescence (CL) of the CdTe nanocrystal (NC)-hydrogen peroxide system and that estrogens inhibited these CL signals in alkaline solution. CL spectra were used to investigate the mechanism of the CL enhancement. On the basis of the inhibition, a flow-injection CL method has been established for determination of three natural estrogens.

catena-Poly[[[(acetato-κO,O')cadmium]-µ-acetato-κO,O':O'-µ-{1,2-bis-[4-(pyridin-3-yl)pyrimidin-2-ylsulfan-yl]ethane}-κN,N] trihydrate].

The title compound, {[Cd(CH(3)COO)(2)(C(20)H(16)N(6)S(2))]·3H(2)O}(n), exists as a one-dimensional zigzag polymer in which the Cd(II) ion shows a seven-coordinate [CdO(5)N(2)] distorted penta-gonal-bipyramidal geometry with the N atoms in axial positions and an N-Cd-N angle of 176.94 (13)°. The metal atoms are bridged by 1,2-bis-[4-(pyridin-3-yl)pyrimidin-2-ylsulfan-yl]ethane ligands, giving a polymeric chain extending along the b axis. Adjacent chains related by an inversion center are further bridged by Cd-O bonds formed between the O atom of one of the acetate ligands and the metal atom. The five Cd-O bond lengths are in the range 2.329 (3)-2.485 (3) Å. There are π-π stacking inter-actions between the aromatic rings of adjacent polymeric chains, the centroid-centroid distances being 3.556 (3) and 3.698 (3) Å, organizing the chains into a three-dimensional framework. This framework is additionally stabilized by extensive O-H⋯O and O-H⋯N hydrogen bonding between water mol-ecules and the ligands.

Self-assembly of copper and cobalt complexes with hierarchical size and catalytic properties for hydroxylation of phenol.

A feasible and effective self-assembly method to synthesize different scale coordination polymers in highly dilute solution (from nanocrystals to microcrystals and to bulk crystals) without any blocking agent has been described. The growth of crystalline particles was controlled by removing the particles at different reaction times to interrupt the growth at the desired size. The nano and microscale particles show better catalytic conversions and selectivities in the hydroxylation of phenols than the bulk crystals.

2-{[4-(Pyridin-2-yl)pyrimidin-2-yl]sulfan-yl}acetic acid.

In the title mol-ecule, C(11)H(9)N(3)O(2)S, the pyridine and pyrimidine rings are almost parallel [dihedral angle = 6.7 (1)°]. In the crystal, adjacent mol-ecules are joined by O-H⋯N and C-H⋯O hydrogen bonds, leading to the formation of a sheet parallel to (10[Formula: see text]).

Hexaaqua-magnesium(II) bis-[4-(3-pyrid-yl)pyrimidine-2-sulfonate] tetra-hydrate.

The asymmetric unit of the title compound, [Mg(H(2)O)(6)](C(9)H(6)N(3)O(3)S)(2)·4H(2)O, contains half of a centrosymmetric cation, one 4-(3-pyrid-yl)pyrimidin-2-sulfonate anion and two solvent water mol-ecules. Inter-molecular O-H⋯O and O-H⋯N hydrogen bonds link the cations, anions and water mol-ecules into a three-dimensional supra-molecular structure. The crystal packing also exhibits inter-molecular π-π inter-actions between the aromatic rings of the anions with a centroid-centroid distance of 3.604 (2) Å.

cis-1,2-Bis{[4-(4-pyrid-yl)pyrimidin-2-yl]sulfanylmeth-yl}benzene.

The mol-ecular skeleton of the title mol-ecule, C(26)H(20)N(6)S(2), adopts a cis conformation with the two arms positioned on one side of the benzene ring plane. Intra-molecular π-π inter-actions between the pyrimidine rings [centroid-centroid distance = 3.654 (2) Å] and between the pyridine rings [centroid-centroid distance = 3.775 (2) Å] help to set the mol-ecular conformation; the pyrimidine rings, as well as the pyridine rings, are nearly parallel, forming dihedral angles of 4.12 (14) and 2.46 (14)°, respectively.

Diaqua-dibromidobis[3-dimethyl-amino-1-(4-pyridyl-κN)prop-2-en-1-one]cadmium(II).

In the title compound, [CdBr(2)(C(10)H(12)N(2)O)(2)(H(2)O)(2)], the Cd(II) ion is located on an inversion center and is six-coordinated by two N atoms [Cd-N = 2.377 (3) Å] from two different 3-dimethyl-amino-1-(4-pyrid-yl)prop-2-en-1-one ligands, two O atoms [Cd-O = 2.355 (2) Å] from two coordinated water mol-ecules and two bromide anions [Cd-Br = 2.6855 (5) Å]. Inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into layers parallel to the bc plane.

Anion-modulated reversible conversion of molecular assembly between a macrocycle and a linear chain.

Interaction of a flexible thioether ligand with mercury(II) acetate and iodide, respectively, yielded two compounds with structural motifs of a macrocycle and a 1D polymer, whose structural patterns were dominated by anions and could be reversibly changed.

1,3-Bis[4-(4-pyrid-yl)pyrimidin-2-ylsulfan-yl]propane.

In the title compound, C(21)H(18)N(6)S(2), the dihedral angles between the aromatic rings in the two 4-(4-pyrid-yl)pyrimidine residues are 23.45 (13) and 2.67 (14)°. Whereas one of the C-S-C-C torsion angles corresponds to a staggered conformation, the other is gauche.

2,2'-(p-Phenyl-ene)bis-(1,4,5,6-tetra-hydro-pyrimidinium) bis-[dicyanidoargentate(I)].

The asymmetric unit of the title compound, (C(14)H(20)N(4))[Ag(CN)(2)](2), contains one-half of a centrosymmetric 2,2'-(p-phenyl-ene)bis-(1,4,5,6-tetra-hydro-pyrimidinium) (H(2)btb) cation and one [Ag(CN)(2)](-) anion. In the anions, the Ag(I) atoms adopt near linear coordination modes with the two attached cyanide groups [C-Ag-C = 173.3 (2)°]. In the crystal structure, each H(2)btb cation links four [Ag(CN)(2)](-) anions via N-H⋯N hydrogen bonds into a one-dimensional ribbon.

Poly[{µ(2)-1,2-bis-[4-(3-pyrid-yl)pyrimidin-2-ylsulfan-yl]ethane}di-µ(2)-cyanido-dicopper(I)].

The asymmetric unit of the title complex, [Cu(2)(CN)(2)(C(20)H(16)N(6)S(2))](n), contains one Cu(I) cation, one cyanide ligand and half of a centrosymmetric 1,2-bis-[4-(3-pyrid-yl)pyrimidin-2-ylsulfan-yl]ethane (bppe) ligand. The Cu(I) atom displays a trigonal coordination geometry, being surrounded by one C atom from one cyanide anion and two N atoms from one cyanide and one bppe ligand. In the complex, each cyanide anion links two Cu(I) atoms in a bis-monodentate mode into a zigzag [-Cu-CN-](n) chain. Two parallel chains are linked by bppe ligands into a ladder chain.

3,6-Di-4-pyridyl-1,4-dihydro-1,2,4,5-tetra-zine.

The mol-ecule of the title compound, C(12)H(10)N(6), which is V-shaped due to the boat conformation of the dihydro-tetra-zine ring, has crystallographic C(2) symmetry. The dihedral angle between the planes of the two pyridine rings is 31.57 (3)°. Mol-ecules are linked by weak N-H⋯N and C-H⋯N hydrogen bonds, forming a two-dimensional polymeric structure.