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The coordination interactions between transition-metal ions (Cu 2+ , Ag + ) and sulfur atoms on ultrathin two-dimensional (2D) nanosheets of spin-crossover (SCO) metal-organic frameworks {[Fe(1,3-bpp) 2 (NCS) 2 ] 2 } n (1,3-bpp = 1,3-di(4-pyridyl)propane), which constructed the ultrathin 2D nanosheets into three-dimensional (3D) nanoparticles, have made a profound effect on the SCO performance. Compared with 2D nanosheets, both the intraligand π-π* transition band and the metal-to-ligand charge transition band from the d(Fe) + π(NCS) to π*(1,3-bpp), for the 3D nanoparticles, have shown dramatic blue-shifts; meanwhile, the d-d transition band for the high-spin (HS) state Fe(II) ions has been generated, suggesting significantly the influence of 3D assemble-caused dimensional changes on the solid-state SCO performance of ultrathin 2D nanosheets. More importantly, by loading on the ytterbium ion (Yb 3+ )-sensitized hexagonal phase upconverting nanoparticles in the aqueous colloidal suspension, the near infrared (NIR) light (980 nm) triggered HS (high spin) to LS (low spin) state transitions have been observed, demonstrating the achievement of challenging target of NIR light-triggered molecular conversion under environment conditions.

Precise revealing the mechanisms of excited-state intermolecular proton transfer (ESPT) and the corresponding geometrical relaxation upon photoexcitation and photoionization remains a formidable challenge. In this work, the compound (E)-4-(((4H-1,2,4-triazol-4-yl)imino)methyl)-2,6-dimethoxyphenol (TIMDP) adopting a D-π-A molecular architecture featuring a significant intramolecular charge transfer (ICT) effect has been designed. With the presence of perchloric acid (35 %), TIMDP can be dissolved through the formation of a HClO 4 -H 2 O-OH(TIMDP)-N(TIMDP) hydrogen-bonding bridge. At the ground state, the ICT effect is dominant, giving birth to crystals of TIMDP. Upon external stimuli (e.g., UV light irradiation, electro field), the excited state is achieved, which weakens the ICT effect, and significantly promotes the ESPT effect along the hydrogen-bonding bridge, resulting in crystals of [HTIMDP] + ⋅[H 2 O]⋅[ClO 4 ] - . As a consequence, the mechanisms of the ESPT can be investigated, which distorted the D-π-A molecular architecture, tuned the emission color with the largest Stokes shift of 242 nm, and finally, high photoluminescence quantum yields (12 %) and long fluorescence lifetimes (8.6 μs) have achieved. These results not only provide new insight into ESPT mechanisms, but also open a new avenue for the design of efficient ESPT emitters., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The design and preparation of a porous high-valence metal-organic framework (MOF) featuring open coordination sites are of utmost importance for the development of adsorbent materials. Here in this work, the three-dimensional (3D) high-valence MOF [Er(dcbp) 3/2 (DMF)(H 2 O) 2 ]·2H 2 O (HV-MOF-1; H 2 dcbp = 4,4'-dicarboxy-2,2'-bipyridine, DMF = N,N-dimethylformamide), which possesses permanent porosity and two open coordination sites, has been prepared and characterized. In the 3D framework, the dcbp molecules display two different bridging styles, resulting in ordered diamondlike pores with bared carboxyl oxygen and pyridine nitrogen atoms on dcbp exposed directly to the pores, generating hydrophilic characteristics and high water affinity. In addition, the open coordination sites act as arms to fix the adsorbed water molecules, providing high water adsorption capacity (5.95 mmol g -1 ) and selectivity. More importantly, the activated HV-MOF-1 species shows an energy-saving step for recycling (operation under 120 °C), demonstrating promise as a candidate for an adsorbent material with considerable water adsorption-desorption cycles.

Cisplatin is a highly effective antitumor drug, which can kill cancer cells by crossing-linking DNA and inhibiting transcription, but this process is limited by the combination of cisplatin and many endogenous nucleophiles, such as glutathione (GSH). Thus, when cisplatin enter cells, it is potentially vulnerable to cytoplasmic inactivation by GSH. To settle this bottleneck, we designed and synthesized a probe compound (Probe 1) and fabricated pH-responsed cisplatin, Probe 1-loaded lipid-polymer hybrid NanoParticles (CPNPs) using a single-step sonication method. Probe 1 can specifically bind to GSH, thus avoiding the combination of GSH and cisplatin, and enhancing the pharmacological activity of cisplatin. In vitro studies have suggested CPNPs, compared with cisplatin, loaded lipid-polymer hybrid NanoParticles CNPs (Not contain Probe 1), could efficiently kill MCF-7 human breast cancer cells and A549 human nonsmall lung cancer cell. Hence, the CPNPs provided a new idea for treating cancer., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Subtle integration of rotatable polar components into dielectric crystals can contribute significantly to adjustable switching temperatures ( T s ) and dielectric relaxation behaviors. Currently, one of the biggest challenges lies in the design of optimal polar components with moderate motion resistance in a crystalline system. In this work, we demonstrate that under refrigerator conditions, rotatable hydrogen-bonded one-dimensional (1D) cationic chains, {[C 2 H 6 N 5 ] + } n (C 2 H 6 N 5 = 3,5-diamino-1,2,4-triazolinium), and two-dimensional (2D) anionic layers, {[(H 2 O) 2 ·SO 4 ] 2- } n , can be generated in an organic salt, 3 ([C 2 H 6 N 5 ] 2 ·[(H 2 O) 2 ·SO 4 ]). Compared with the nonhydrated precursor, 2 ([C 2 H 7 N 5 ]·[SO 4 ]), the rotation of these 1D and 2D ionic species triggers a reversible phase transition and dielectric switching in 3. In addition, the significantly sluggish rotation of the 1D cationic chains from parallel to unparallel stacking and the counter-clockwise rotation of the 2D anionic layers, compared with their reverse processes, induce a frequency-dependent dielectric response with a more highly adjustable heating T s ↑ than the cooling T s ↓. More importantly, 3 possesses excellent self-recovery ability attributed to the highly dynamic character of the hydrogen-bonded ionic species. The strategy here can provide a fairly good model for designing dielectric crystals with desired rotatable polar components.

Combining the fascinating advantages of ultrathin two-dimensional (2D) nanosheets with the nanostructuration of spin-crossover (SCO) materials represents an attractive target of controlled fabrication of SCO nano-objects at the device level. Here, we demonstrate that through facile-operating ultrasonic force-assisted liquid exfoliation technology the three-dimensional (3D) van der Waals SCO bulk precursor {[Fe(1,3-bpp) 2 (NCS) 2 ] 2 (1, 1,3-bpp = 1,3-di(4-pyridyl)-propane)} can be exfoliated into single-layered 2D nanosheets (NS-1). As a consequence, the magnetism has been tuned from complete paramagnetic (bulk precursors) to SCO transition at around 250 K (2D nanosheets). In addition, the metal-to-ligand charge transition (MLCT), the intraligand π-π* transition and the color display also have been altered both in colloidal suspension and in the solid state. These dramatic changes of physical-chemical properties at different forms and states can be attributed to the efficient cooperativity derived from the interlayer van der Waals interactions within the curly or vertically stacked 2D building blocks.

The co-delivery of two or more anti-tumor agents using nanocarriers has shown great promise in cancer therapy, but more work is needed to selectively target drugs to specific subcellular organelles. To this end, our research has reported on "smart" polymeric nanoparticles that can encapsulate two different site-oriented pro-drug molecules, allowing them to reach their targeted subcellular organelles based on NIR-mediated controlled release, allowing for targeted modifications in the nucleus or the mitochondria. Specially, an all-trans retinoic acid (RA) conjugated cisplatin derivative (RA-Pt) can be delivered with high affinity to the nucleus of target cells, facilitating the binding of cisplatin to double-stranded DNA. Similarly, a synthesized derivative generated by conjugation of triphenylphosphine (TPP) and celastrol (TPP-Cet) may facilitate mitochondrial targeted drug delivery in tumor cells, inducing ROS accumulation and thereby leading to apoptosis. Relative to nanoparticles loaded with a single therapeutic agent, dual antitumor agent-loaded nanocarriers showed promising synergy, exhibiting significant tumor inhibition in vivo (81.5%), and less systemic toxicity than the free therapeutic agents alone or the drug-loaded nanoparticles without targeted ligands. These results indicated that site-oriented payloads can effectively enhance antitumor therapeutic efficiency and these studies offer a novel "multistage targeted-delivery" strategy in synergistic therapy for cancer treatment.

Through a facile-operating ultrasonic force-assisted liquid exfoliation technology, the single-layered two-dimensional (2D) [Co(CNS) 2 (pyz) 2 ] n (pyz = pyrazine) nanosheets, with a thickness of sub-1.0 nm, have been prepared from the bulk precursors. The atomically thickness and the presence of abundant sulfur atoms with high electronegativity arrayed on the double surfaces of the sheets are making this kind of 2D MOF (metal-organic framework) nanosheets highly sensitive to intermolecular interactions. As a result, it can be well dispersed in all kinds of solvents to give a stable colloidal suspension that can be maintained for at least one month, accompanied by significant solvatochromic behavior and various optical properties, which thus have shown the potential to be practically applicated as in situ visual test paper for solvent identification and solvent polarity measurements. More importantly, combined with a smartphone, this kind of 2D-MOF nanosheets can be developed into in situ visual test paper to identify isomers and determine the polarity of mixed solvents quantitatively and qualitatively, suggesting the promising application of a portable, economical, and in situ visual test strategy in real world.

Bidirectional photoswitching of molecular materials under ambient condition is of significant importance. Herein, we present for the first time that a core-shell UCNP-SCO nanosphere (UCNP = upconversion nanophosphor, SCO = spin crossover), which was composed of a UCNP core (NaYF 4 : 20 mol % Yb 3+ , 1 mol % Er 3+ ) and an SCO iron(II) shell ([Fe(H 2 Bpz) 2 (bipy-COOH)], H 2 Bpz = dihydrobis(1-pyrazolyl)borate, bipy-COOH = 4,4'-dicarboxy-2,2'-bipyridine), can be reversibly photoswitched between the high-spin and low-spin states at room temperature in the solid state, via alternating irradiation with near-infrared (λ = 980 nm) and ultraviolet (λ = 310 nm) light. What's more, this reversible spin-state switching was accompanied by a variation of fluorescent spectrum and dielectric constants. The strategy here, that is, integrating the SCO iron(II) complex into a UCNP-SCO nanosphere for molecular photoswitching, may open a new area in the development of photocontrolled molecular devices.

A thermal-induced dielectric switching has been realized in two ion-pair crystal [C 2 H 6 N 5 ] + ·[H 2 PO 4 ] - (1, C 2 H 6 N 5 = 3,5-diamino-1,2,4-triazolinium) through single-crystal-to-single-crystal phase transition (SCSC-PT). Upon cooling from room temperature, the 1D cation stripes that are composed of [C 2 H 5 N 5 ] + cations have undergone a 90° sharp rotation around the c axis, accompanied by the transition of crystal stacking from loose unparallel (dynamic state) to compression parallel (static state) and reorientation of dipoles on the [C 2 H 5 N 5 ] + cation, which thus resulted in high dielectric state to low dielectric state transformation. While on the warming run, the reverse process was rather sluggish, resulting in a reversible dielectric switching with ultralarge (about 40K wide) hysteresis loop near room temperature. It is thought that the large-sized polar cation stripes have a predominant influence on the switching properties of 1.

The organometallic cation 1 (Fe(bipy-NH 2 ) 3 2+ , bipy-NH 2 = 4,4'-diamino-2,2'-bipyridine), which was constructed in situ in solution, can bind CO 2 from air effectively with a stoichiometric ratio of 1:4 (1/CO 2 ), through the formation of "H-bonded CO 2 " species: [CO 2 -OH-CO 2 ] - and [CO 2 -CO 2 -OH] - . These two species, along with the captured individual CO 2 molecules, connected 1 into a novel 3D (three-dimensional) architecture, that was crystal 1·2(OH - )·4(CO 2 ). The adsorption isotherms, recycling investigations, and the heat capacity of 1 have been investigated; the results revealed that the organometallic cation 1 can be recycled at least 10 times for the real-world CO 2 capture applications. The strategies presented here may provide new hints for the development of new alkanolamine-related absorbents or technologies for CO 2 capture and sequestration.

Four new complexes, [Co(dmbpy)2(dca)2]·CH3OH (1), [Ni(dmbpy)2(dca)2]·CH3OH (2), [Zn(dmbpy)2(dca)2]·(3) and [Cu(dmbpy)2(OH)2]·5H2O (4) (dca=dicyanamide), derived from 4,4'-dimethyl-2,2'-bipyridine (dmbpy) have been synthesized and characterized by elemental analysis, TGA and single-crystal X-ray diffraction. Crystal structures and Hirshfeld surfaces analysis revealed that the complexes 1-3 were mainly supported by OH⋯N, CH⋯N and π⋯π intermolecular interactions, and for complex 4, the uncoordinated water molecules play a key role in the construction of the 3D stacking motif. UV spectrum measurements demonstrate that all of the complexes show typical metal to ligand charge transfer (MLCT) absorption bands between 301 and 306nm. Moreover, after complexation, the absorption maximum bands about intraligand π→π* transitions similarly show slightly red shift compared to dmbpy ligand, consisting with the DFT calculations., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Antibody drug conjugates (ADCs) are an emerging class of targeted therapeutics with the potential to improve therapeutic index over the traditional chemotherapy. However, it is difficult to control the site and stoichiometry of conjugation in mAb, typically resulting in heterogeneous mixtures of ADCs that are difficult to optimize. New methods for site-specific drug attachment allow development of more homogeneous conjugates and control of the site of drug attachment. In this article, the new literature on development of ADCs and site-specific ADCs is reviewed. In addition, we summarized the various strategies in production of site-specific ADCs.

Two copper complexes 1 [Cu2(phen)2(salicylaldehyde)2(ClO4)2] and 2 [Cu2 (2,2'-dipyridyl)2(salicylaldehyde)2(ClO4)2] have been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. These two complexes were display binuclear structure with Cu(II) ions in distorted octahedral environment but antipodal orientation of the binuclear units between them. Molecular Hirshfeld surfaces revealed that the crystal structures of 1 and 2 were supported mainly by H-H, C-H⋯π, π⋯π (C-C), and C-H⋯O intermolecular interactions. DNA cleavage experiments of complexes 1 and 2 revealed that these complexes can intercalation with DNA., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Three new co-crystals: pyridine-2-carboxamide-succinic acid (1), pyridine-2-carboxamide-glutaric acid (2) and pyridine-2-carboxamide-adipic acid (3) have been synthesized and characterized by single-crystal X-ray diffraction, TGA/DSC measurements, solid-state vibrational spectroscopy (IR and Raman) in this work. The investigation revealed that the carbon chain length of these alkyl acids changed the connecting motif of co-crystals 1-3 from trimer to 1D chain, and the formation of hydrogen bond interaction of pyridine-2-carboxamide with these alkyl acids lead to red shift of stretching vibration of NH2 and OH groups in IR and Raman spectra. We also studied Hirshfeld surface and UV properties of co-crystals 1-3, and we found that the carbon chain length lead to decrease of close intermolecular interactions, and the formation of hydrogen bond interaction lead to red shift of UV spectra., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Two new metastable crystalline forms of 6-chloroquinolin-2(1H)-one (forms II and III), which were induced by two kinds of 3D inorganic anions (ClO4- and BF4-), have been prepared and characterized in this work. We performed single-crystal diffraction, X-ray powder diffraction (XRPD), Hirshfeld surfaces, solid-state vibrational spectroscopy (IR) and thermal analysis (DSC, TGA) to these two new forms as well as the original one (form I). Form I featured with 1D chain, while form II and III featured with dimeric unit with stronger π⋯π and hydrogen bonds interactions. The 3D inorganic anions force the self-assemble behavior of 6-chloroquinolin-2(1H)-one molecules from 1D chain structure (form I) to dimeric unit (forms II and III) due to their large steric hindrance, and different anions induced different orientations for dimeric unit. These transformations lead to the increase of N-H⋯O, π⋯π, and Cl-Cl intermolecular interactions, which lead to blue shift of IR spectra in 1700-1500 cm(-1) region as well as luminescence peaks, while red shift of IR spectra in 650-550 cm(-1) region., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Traditional chemotherapy has become one of the essential treatments of cancer. However, cytotoxic agents are not tumor specific, which would cause serious side effects. Antibody-drug conjugates (ADCs), also called immunoconjugates, belong to the "targeted chemotherapeutics" category of anti-cancer drugs. ADCs are composed of three components including the cytotoxic drug, the monoclonal antibody, and the linker connecting the drug to the antibody. With the special-binding between antibody and antigen expressed on the surface of targeted cancer cells, ADCs provide a method to achieve excellent localization of the drug at the desired site in the body. The internalization and formation of ADCs are crucial in designing and applying an antibody conjugate to a particular disease model. In this review, we summarize three distinct internalization routes of ADCs and analysis the structure of ADCs. We also discuss in detail the categories and interaction of every component, as well as their influence to targeting property, liability and activity.

In the mononuclear title complex, [Cu(C(14)H(13)N(2)O(2))(2)], the Cu(II) atom lies on an inversion centre and adopts a square-planar coordination geometry. The dihedral angle formed by the pyridine and benzene rings is 74.61 (5)°. Intra-molecular C-H⋯O hydrogen bonds are present. The crystal structure is stabilized by weak aromatic π-π stacking inter-actions involving neighbouring pyridine rings [centroid-centroid distance = 3.853 (2) Å].

In the title compound, [Co(C(5)H(9)O(2))(2)(C(12)H(8)N(2))(H(2)O)], the Co(II) atom is coordinated in a distorted octahedral environment by three carboxyl O atoms of two trimethyl-acetate ligands, one aqua O atom and two N atoms from 1,10-phen-anthroline. The crystal structure is stabilized by O-H⋯O hydrogen bonds and π-π stacking inter-actions [inter-planar distance between inter-digitating 1,10-phenanthroline ligands = 3.378 (2) Å].

The title complex, [Co(2)Cl(4)(C(10)H(8)N(2))(2)(H(2)O)(2)], is composed of two Co(II) atoms, each hexa-coordinated by three Cl atoms, one 2,2'-bipyridine (bpy) ligand and one water mol-ecule in a distorted octa-hedral geometry. Neighboring Co(II) atoms are linked together by two Cl bridges, forming a dinuclear Co(II) complex with inversion symmetry. There are inter-molecular O-H⋯Cl hydrogen bonds and inter-molecular π-π stacking inter-actions between adjacent bpy ligands [centroid-centroid distance = 3.617 (2) Å] in the structure.

In the dinuclear centrosymmetric copper(II) title compound, [Cu(2)(C(11)H(11)N(2)O(2))(2)Cl(2)(H(2)O)(2)], each Cu(II) ion has a slightly distorted trigonal-bipyramidal geometry and is coordinated by one N and one O atom from one 3-(2-hydroxy-ethyl)-2-methyl-4-oxopyrido[1,2-a]pyrimidin-9-olate ligand, another O atom from the second ligand, one water mol-ecule and one Cl atom. The crystal structure involves inter-molecular C-H⋯Cl, O-H⋯Cl and O-H⋯O hydrogen bonds.

In the title compound, C(16)H(18)N(2)O(8)S, derived from ranelic acid, there is a highly substituted thio-phene ring. The crystal structure involves inter-molecular C-H⋯O and C-H⋯S hydrogen bonds.

In the title compound, C(12)H(12)N(2)O, the dihedral angle between the planes of the pyridine and phenyl rings plane is 35.94 (12)°. In the crystal structure, centrosymmetrically related mol-ecules are linked by a pair of N-H⋯N hydrogen bonds, forming a dimer with an R(2) (2)(8) ring motif. In addition, there is an intra-molecular N-H⋯O inter-action.

The title compound, [Zn(C(2)N(3))(2)(C(12)H(9)NO)(2)](n), is a polymeric zinc(II) complex with the metal ion located on an inversion centre. The Zn(II) ion is six-coordinated by two N atoms of two 3-benzoyl-pyridine ligands and four N atoms from four dicyanamide ligands, forming a slightly distorted octa-hedral configuration. In the crystal structure, neighboring Zn atoms are linked together by double dicyanamide bridges to form a polymeric zinc(II) complex.

The title polymeric compound, [Mn(2)(C(10)H(2)O(8))(C(12)H(8)N(2))(2)](n), was obtained by the reaction of manganese(II) chloride tetra-hydrate with benzene-1,2,4,5-tetra-carboxylic acid (H(4)bta) in aqueous solution. Each Mn(2+) ion is coordinated in a distorted octa-hedral geometry by two N atoms from one 1,10-phenanthroline ligand and four O atoms [Mn-O = 2.116 (2)-2.237 (2) Å] from three bta(4-) ligands, which also act as bridging groups between the Mn(2+) ions.

In the title compound, C(12)H(16)N(3)O(2)·C(2)HCl(3)O(2), the imidazolidine ring adopts a twist conformation. The crystal structure is stabilized by inter-molecular O-H⋯N hydrogen bonds.

In the title compound, [Cd(2)(C(6)H(4)NO(3))(2)(N(3))(2)(H(2)O)(2)](n), one Cd(II) atom is located on an inversion center and is coordinated by four O atoms from four bridging 1-oxoisonicotinate ligands and two N atoms of two bridging azide ligands in a slightly distorted octa-hedral geometry. The other Cd(II) atom, also lying on an inversion center, is coordinated by four O atoms from two bridging 1-oxoisonicotinate ligands and two water mol-ecules and two N atoms of two bridging azide ligands in a slightly distorted octa-hedral geometry. The Cd atoms are connected via the 1-oxoisonicotinate and azide ligands into a two-dimensional coordination network. The crystal structure involves O-H⋯N and O-H⋯O hydrogen bonds.

The title compound, [Os(3)(C(9)H(6)NS)H(CO)(10)], contains a nearly equilateral triangle of Os atoms. Two of the Os atoms are bridged by an S atom of the quinoline-2-thiol-ate ligand. Ten carbonyl groups complete the cluster, resulting in a distorted octa-hedral geometry for each Os atom. The hydride atom, which was located in a difference Fourier map and refined isotropically, bridges the shortest Os-Os edge.

The title coordination polymer, {[Ag(C(12)H(11)N(3)O)]NO(3)·H(2)O}(n), has a polycationic chain motif in which the Ag atom is bridged by the heterocyclic ligand; the Ag atom shows linear coordination. If the two long Ag⋯O(nitrate) inter-actions [2.794 (6) and 2.867 (5) Å] are regarded as bonds, the compound adopts a three-dimensional network structure. The water mol-ecule consolidates the network structure by forming hydrogen bonds, one to the polycationic chain and one to the nitrate anion.

The title compound, [Cu(C(11)H(11)NO(5))(H(2)O)](n), was obtained by the reaction of Cu(NO(3))(2) and the homochiral organic ligand (S)-N-(2-hydroxy-benz-yl)-l-aspartic acid (S-H(3)sasp). The Cu(II) ion has a distorted square-pyramidal geometry and is coordinated by one N atom and three O atoms from the organic ligand and one O atom from a water mol-ecule. The carboxyl O atoms of the ligands bridge the Cu atoms to form an infinite one-dimensional zigzag chain. Inter-molecular hydrogen bonds link these chains into a two-dimensional arrangement.

In the title compound, [Zn(C(6)H(4)NO(3))(2)(H(2)O)(2)], the Zn atom is located on a centre of inversion and shows a distorted octa-hedral coordination geometry. Two aqua ligands occupy the axial positions and four O atoms of the two chelating picolinic acid N-oxide ligands are located in the equatorial plane. Inter-molecular hydrogen bonds between aqua ligands and organic ligands link mol-ecules into a two-dimensional arrangement.

The title compounds are isomorphous, comprised of neutral monomeric [M(phen)(2)(dca)(2)] [(I): M = Mn, (II): M = Zn; phen is 1,10-phenanthroline, C(12)H(8)N(2); dca is dicyanamide, C(2)N(3)] molecules. In the molecule, the divalent metal ion is in a distorted octahedral coordination environment formed by six N atoms from the phen and dca ligands. The Mn-N [2.144 (2)-2.319 (2) A] and Zn-N [2.075 (2)-2.245 (2) A] distances are in agreement with the difference in size of the two divalent ions.