Identification of intramolecular hydrogen bonds as the origin of malfunctioning of multitopic receptors

Zn-coordination polymers for fluorescence sensing various contaminants in water

Luminescent coordination polymers (LCPs) have garnered significant attention from researchers as promising materials for detecting contaminants. In this paper, three new LCPs ([Zn(tib)(opda)]n⋅H2O (1), [Zn3(tib)2(mpda)3]n⋅5H2O (2), [Zn (tib)(ppda)]n⋅H2O (3)) with different structures (LCP 1-3: 1D, 2D, 1D) using phenylenediacetic acid isomers and 1,3,5-tris (1-imidazolyl) benzene (tib) are synthesized. The specific surface areas (BET) of LCP 1-3 are 4 m2/g, 19 m2/g, and 13 m2/g respectively. LCP 1-3 exhibit excellent fluorescence properties and can serve as fluorescent probe for the detection of inorganic contaminants and organic contaminants. Due to the large BET of LCP 2, the detection limits for trace analytes surpass those of LCP 1 and 3. The detection limits of LCP 2 for Fe3+, nitrobenzene (NB), chloramphenicol (CAP), and pyrimethanil (PTH) are 8.3 nM, 0.016 μM, 0.19 μM, and 0.032 μM, respectively, and the fluorescence quenching rates are 98.6 %, 98.8 %, 92.3 %, and 98.8 %, respectively. These values outperform most reported in the literature. The quantum yields of LCP 1-3 are 11.84 %, 25.22 %, 22.00 % respectively. Real sample testing of LCP 1-3 reveals favorable performance, where spiked recoveries of LCP 2 for the detection of pyrimethanil in grape skins ranged from 99.62 % to 119.3 % with a relative standard deviation (RSD) of 0.627 % to 4.56 % (n = 3). The fluorescence quenching mechanism was attributed to a combination of photoelectron transfer (PET), resonance energy transfer (RET), and competitive absorption (CA). This study advances the application of LCPs in luminescence sensing and contributes to the expansion of novel materials for detecting environmental pollutants.

Fabrication of a Co-Mo-Based Metal-Organic Framework for Growth of Double-Walled Carbon Nanotubes

Double-walled carbon nanotubes (DWCNTs) make up a unique class of carbon nanotubes (CNTs) that are particularly intriguing for scientific research and are promising candidates for technological applications. A more precise level of control and greater yields can be achieved via catalytic chemical vapor deposition (CCVD), which involves the breakdown of a carbonaceous gas over nanoparticles. The addition of molybdenum to the system can increase the selectivity with regard to the number of walls that exist in the obtained CNTs. As reported herein, we have designed and synthesized a novel Co-Mo-MOF, [Co(3-bpta)1.5(MoO4)]·H2O (where 3-bpta = N,N'-bis(3-pyridyl)terephthalamide), and employed the Co-Mo-MOF as a bimetallic catalyst precursor for the CCVD approach to prepare high-quality DWCNTs. The Co-Mo-MOF was employed after being calcined in N2 and H2 at 1100 °C and decomposing into CoO, CoMoO4, and MoO3. Existing CoMoO4 is unaltered after reduction in H2 at 1100 °C, while CoO and MoO3 are converted into Co0 and MoO2, and more CoMoO4 is created at the expense of Co0 and MoO2 without clearly defining agglomeration. Finally, the interaction between metallic Co particles and C2H4 is what initiates the formation of DWCNTs. In-depth discussion is provided in this paper regarding the mechanism underlying the high selectivity and activity of Co-Mo catalysts in regulating the development and structure of DWCNTs. The DWCNTs also offer excellence performance when they are used as water purification agents and as selective sorbents. This work opens a feasible way to use MOFs as a way to produce MWCNTs, thus blazing a new trail in the field of MOF-derived carbon-based materials.

A new three-dimensional zinc(II) metal-organic framework as a fluorescence sensor for sensing the biomarker 3-nitrotyrosine

3-Nitrotyrosine (3-NT), an oxidative stress biomarker, is closely associated with various diseases. Thus, rapid and sensitive detection of 3-NT is of great significance for preventing and treating diseases. Herein, we reported a new 3D zinc-based metal-organic framework (Zn-MOF) [Zn(L)(HBTC)] (L = (E)-4,4'-(ethene-1,2-diyl)bis[(N-pyridin-3-yl)benzamide], H₃BTC = 1,3,5-benzenetricarboxylic acid), which was structurally characterized by single crystal X-ray diffraction, IR, PXRD and TG. The Zn-MOF can be used as a highly efficient fluorescence sensing material to provide a direct and low-cost method for the rapid detection of 3-NT and shows high sensitivity with a K_SV value of 6.596 × 10⁴ M^-1, a rapid luminescence response within 24 s, excellent selectivity, high anti-interference ability and good recyclability. It is the first example of a MOF being used to directly detect 3-NT as a luminescence sensor to our knowledge. The sensing mechanism of the Zn-MOF towards 3-NT is discussed in detail, which provides a basis for the rational design of MOF sensing materials and their application in biomarker detection.

Cobalt complexes tuned by Anderson-type polyoxometalates and bis-amide derivative ligands featuring a 'V'-like connector for efficient ampere sensing and the visible-light catalytic reduction of Cr(VI)

To exploit polyoxometalate (POM)-based metal-organic complexes (MOCs) with outstanding electro- and photo-chemical performances, two new bis-amide derivative N-donor ligands featuring a 'V'-like connector, 4,4'-bis(3-pyridinecarboxamide)phenylmethane (L¹) and 4,4'-bis(3-pyridinecarboxamide)phenylketone (L²), were designed and reacted with Anderson-type POMs in the presence of Co(II) ions under solvothermal conditions, which generated four MOCs: [Co₂(L¹)₂(AlMo₆H₅O₂₄)]·4H₂O (1), [Co₂(HL¹)₂(H₂O)₆(TeMo₆O₂₄)]·2H₂O (2), [Co₂(HL²)₂(H₂O)₄[AlMo₆H₆O₂₄]₂]·5H₂O (3), and [Co₂(HL²)₂(H₂O)₆(TeMo₆O₂₄)]·2H₂O (4). All the complexes showed supramolecular structures via hydrogen bond interaction, which resulted from the 2D layers for 1, the satellite-like structural units for 2 and 4, but the 1D chains for 3. In these structures, the POMs and organic ligands exhibited different coordination modes. Both 2 and 4 showed efficient ampere sensing activities for Cr(VI) with lower limits of detection of 0.029 and 0.038 μM, respectively. Complexes 1 and 2 showed good visible-light catalytic behavior toward the reduction of Cr(VI), which offers more chances for developing electrochemical sensors and photocatalysts for Cr(VI).

Improvement of the fluorescent sensing biomarker 3-nitrotyrosine for a new luminescent coordination polymer by size regulation

A new 3D luminescent coordination polymer (LCP) 1 was synthesized for detecting biomarker 3-nitrotyrosine. By adjusting the reaction conditions, Nano-LCP 1 was synthesized, which has a more lower detection limit compared with LCP 1.

Four Anderson-type [TeMo6O24]6−-based metal–organic complexes with a new bis(pyrimidine)-bis(amide): multifunctional electrochemical and adsorption performances

Four isostructural Anderson-type POM-based metal–organic complexes derived from a new bis(pyrimidine)-bis(amide) ligand were synthesized, showing multifunctional electrochemical sensing activities and good adsorption performances for organic dyes.

Ligand-induced synthesis of two Cu-based coordination polymers and derivation of carbon-coated metal oxide heterojunctions for enhanced photocatalytic degradation

In this study two new Cu-CPs have been constructed as precursors for the preparation of carbon-coated metal oxide heterojunctions. Moreover, we have used Mo metal as a doping agent to boost the photodegradation activity of the CP-derived carbon nanostructures.

Two polymolybdate-directed Zn(ii) complexes tuned by a new bis-pyridine-bis-amide ligand with a diphenylketone spacer for efficient ampere sensing and dye adsorption

Two polymolybdate-based Zn(ii) complexes were constructed from a new bis-pyridine-bis-amide ligand, which can be used as electrocatalysts and electrochemical sensors for Cr(vi), KBrO3, H2O2 and AA, and exhibit selective adsorption of CV and MB.

Synthesis of a 2D Cu@TiO2 composite via the design of a 1D Cu-based coordination polymer precursor for efficient and selective photodegradation of dyes

A 2D Cu@TiO₂ composite with a porous and crystalline structure was successfully synthesized via one-step and low-temperature calcination of a 1D Cu-based coordination polymer (Cu-CP), namely [Cu₂(3-dpha)(1,4-NDC)₂(H₂O)₃]_n (3-dpha = N,N′-bis(3-pyridyl)adipamide and 1,4-H₂NDC = 1,4-naphthalenedicarboxylic acid). Moreover, the Cu@TiO₂ membrane was fabricated by a simple filtration of the as-grown Cu@TiO₂ composite. Compared with the benchmark TiO₂ photocatalyst, the Cu@TiO₂ composite material with high specific surface area and reduced photogenerated electron–hole ratio exhibited good photodegradation activity and durability for gentian violet (GV), which could be attributed to the combined effect of co-doping of Cu and TiO₂ structure. Furthermore, the ˙OH and ˙O₂⁻ radicals were predicted to dominate the photocatalytic process. Therefore, this new efficient photocatalyst is a promising candidate for efficient and selective photodegradation of organic pollutants.

A 2D Cu@TiO₂ composite was synthesized via low-temperature calcination of a 1D Cu-CP. Moreover, the Cu@TiO₂ membrane was fabricated by a simple filtration of the Cu@TiO₂ composite which exhibited selective photodegradation activity for GV.

A series of bis-pyridyl-bis-amide-modulated metal–organic frameworks: formation, transformation and selectivity for the efficient detection of multiple analytes

A series of LMOFs have been structurally characterized, which display a remarkable fluorescence behavior and can be used as outstanding candidates in the selective sensing of multiple analytes with low limits of detection.

Anderson-type polyoxometalate-based complexes constructed from a new ‘V’-like bis-pyridine–bis-amide ligand for selective adsorption of organic dyes and detection of Cr(vi) and Fe(iii) ions

Four isostructural complexes constructed from Anderson-type POM and new ‘V’-like ligands exhibited outstanding selective adsorption capacities for organic dyes, and electrochemical sensing behaviors toward Cr(vi) and Fe(iii) ions.

Three Zn(ii) coordination polymers constructed with a new amide-thiophene-derived bis-pyridyl ligand as ultrasensitive luminescent sensors for Hg(ii) and purines

A new amide-thiophene-derived ligand (4-bpft) was designed and used to construct three LCPs 1–3, which could detect Hg(ii), adenine, and guanine.

The rational design of four multifunctional octamolybdate-based complexes for detecting different ions and removing organic dyes from aqueous solution

Four new octamolybdate-based complexes were obtained and used not only as electrochemical sensors for sensing Cr(vi), Fe(iii), BrO₃⁻, and NO₂⁻ ions, but also as adsorbents to adsorb organic dyes.

A pH-stable Ag(i) multifunctional luminescent sensor for the efficient detection of organic solvents, organochlorine pesticides and heavy metal ions

Developing novel luminescent materials for sensitive and rapid detection of heavy metal ions, organic solvents and organochlorine pesticides is vital for environmental monitoring. Herein, a new Ag(i) luminescent coordination polymer [Ag(3-dpyb)(H₃odpa)]·H₂O (LCP 1) (3-dpyb = N,N′-bis(3-pyridinecarboxamide)-1,4-butane, H₄odpa = 4,4′-oxydiphthalic acid) was obtained by a hydrothermal reaction and characterized by single crystal, powder X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and luminescence spectroscopy. LCP 1 is a three-dimensional (3D) supramolecular framework formed from 1D [Ag-3-dpyb-H₃odpa]_n chains and H-bond interactions. The luminescence sensing study of LCP 1 for recognizing organic solvents, organochlorine pesticides and heavy metal ions was performed, which demonstrated it to be a potential luminescent sensor for Hacac, NB, 2,6-DCN, Fe²⁺, Hg²⁺, and Fe³⁺. Fe²⁺, Hg²⁺, and Fe³⁺ in river water were determined using LCP 1 with satisfying recovery.

3D supramolecular LCP 1 can detect Hacac, NB, 2,6-DCN, Fe²⁺, Hg²⁺, and Fe³⁺ with a low detection limit and pH stability.

A Stable 3D Zn-Coordination Polymer Sensor Based on Dual Luminescent Ligands for Efficient Detection of Multiple Analytes under Acid or Alkaline Environment

A novel 3D luminescent coordination polymer (LCP) [Zn₄(3-dpyb)₂(odpa)₂(H₂O)₃]·4H₂O (1) (3-dpyb = N,N'-bis (3-pyridinecarboxamide)-1,4-butane, H₄ odpa = 4, 4'-oxidiphthalic acid) was successfully synthesized under solvothermal conditions. LCP 1 displays remarkable fluorescent behavior and stability in a wide range of pH values and different pure organic solvents. More importantly, LCP 1 can become an outstanding candidate in the selective sensing of Fe³⁺, Bi³⁺, Cr₂O₇^2-, MnO₄^-, nitrobenzene (NB), acetaldehyde (AH), and acetylacetone (Hacac) under a lower detection limit. The change process of fluorescent intensity of these seven analytes in a diverse pH range indicates that LCP 1 can be an excellent luminescent sensor in multiple acid/base solutions. As far as we know, it is an infrequent example of a CP-based multiresponsive fluorescent sensor for metal cations, oxyanions, and toxic organic solvents under an acid or alkaline environment.

From coordination polymer to carbon nanotube: Preparation, characterization and rapid adsorption capacity toward organic pollutants

A CuI coordination polymer based on the N,N’-bis(3-pyridinecarboxamide)-1,4-butane (3-dpyb) ligand, namely [Cu(3-dpyb)0.5Cl], is hydrothermally synthesized and structurally characterized, and is used as a catalyst precursor to synthesize multi-walled carbon nanotubes. Interestingly, the as-grown multi-walled carbon nanotubes exhibit high performance in removing dyes from solution and can serve as a low-cost and fast adsorbent. In addition, the adsorption behavior of this new adsorbent fits well with the Freundlich isotherm and the pseudo-second-order kinetic model.

Five naphthalene-amide-bridged Ni(ii) complexes: electrochemistry, bifunctional fluorescence responses, removal of contaminants and optimization by CVD

Five multifunctional Ni-CPs based on a new naphthalene-amide and different carboxylates were obtained and exhibited various properties. CNTs were synthesized from the precursors of CPs, showing selective removal of contaminants in water.

Versatile carboxylate-directed structures of ten 1D → 3D Ni(ii) coordination polymers: fluorescence behaviors and electrochemical activities

Ten 1D → 3D Ni(ii) coordination polymers based on a phenyl/methylene-mixed-bridged ligand have been obtained and structurally directed by carboxylates; they show different fluorescence behaviors and electrochemical activities.

Three cobalt-based coordination polymers with tripodal carboxylate and imidazole-containing ligands: syntheses, structures, properties and DFT studies

The tripodal carboxylate ligand can be employed in Co(ii) salt/imidazole-containing ligand systems to generate 1D chain, 2D layer, and 2D to 3D network, and the fluorescence properties of 1–3 and magnetic behavior of 1 and 2 have been investigated.

High quality and high performance adsorption of Congo red using as-grown MWCNTs synthesized over a Co-MOF as a catalyst precursor via the CVD method

A Co-MOF has been synthesized and characterized, which was firstly used as a combined catalyst precursor to synthesize MWCNTs with high performance in the adsorption of CR.

Carbohydrate receptors combining both a macrocyclic building block and flexible side arms as recognition units: binding properties of compounds with CH2OH groups as side arms

New representatives of compounds combining both a macrocyclic building block and two flexible side arms as recognition units were prepared and their binding properties toward selected carbohydrates were evaluated. The aim of this study was to examine the effects of the replacement of the heterocycle-bearing side arms by smaller units, such as hydroxy groups, on the binding capability. The design of this type of receptor was inspired by the participation of the side chain hydroxy group of serine and threonine in the biorecognition of carbohydrates. Such structural modifications enable the recognition of structure-activity relationships, which are of high importance in the development of carbohydrate receptors with predictable binding strength and selectivity.

Diverse polyoxometalate-based metal–organic complexes constructed by a tetrazole- and pyridyl-containing asymmetric amide ligand or its in situ transformed ligand

Four metal–organic complexes constructed from different polyoxoanions and a tetrazole- and pyridyl-containing asymmetric amide ligand or its in situ transformed ligand have been synthesized and structurally characterized.

A series of pyridyl-amide-based ZnII/CdII coordination polymers and their polypyrrole-functionalized composite materials for tuning their photocatalytic properties

Six pyridyl-amide-based Zn^II/Cd^II coordination polymers have been solvothermally synthesized and decorated by polypyrrole for tuning their photocatalytic properties under visible irradiation.

The assembly of thiophene-based bis-pyridyl-bis-amide CoII coordination polymers and their polypyrrole-functionalized hybrid materials for boosting their photocatalytic performances

A series of thiophene-based bis-pyridyl-bis-amide coordination polymers have been synthesized and decorated with polypyrrole for boosting their photocatalytic properties under visible light irradiation.

Improved binding affinity and interesting selectivities of aminopyrimidine-bearing carbohydrate receptors in comparison with their aminopyridine analogues

Due to the problems with the exact prediction of the binding properties of an artificial carbohydrate receptor, the identification of characteristic structural features, having the ability to influence the binding properties in a predictable way, is of high importance. The purpose of our investigation was to examine whether the previously observed higher affinity of 2-aminopyrimidine-bearing carbohydrate receptors in comparison with aminopyridine substituted analogues represents a general tendency of aminopyrimidine-bearing compounds. Systematic binding studies on new compounds consisting of 2-aminopyrimidine groups confirmed such a tendency and allowed the identification of interesting structure-activity relationships. Receptors having different symmetries showed systematic preferences for specific glycosides, which are remarkable for such simple receptor systems. Particularly suitable receptor architectures for the recognition of selected glycosides were identified and represent a valuable base for further developments in this field.

Various pH-Dependent Copper(II) Coordination Architectures Constructed from N,N′-Di(3-pyridyl)succinamide and Two Different Dicarboxylates

Using a bis-pyridyl-bis-amide N,N′-di(3-pyridyl)succinamide (L) and two dicarboxylates as mixed ligands, four 2D copper(ii) metal–organic networks, formulated as [Cu(1,4-chdc)(L)]·3H2O (1), [Cu(1,4-chdc)(L)]·H2O (2), [Cu(2,5-tdc)(L)]·H2O (3), and [Cu(2,5-tdc)(L)]·2H2O (4) (L = N,N′-di(3-pyridyl)succinimide; 1,4-H2chdc = 1,4-cyclohexanedicarboxylic acid; 2,5-H2tdc = thiophen-2,5-dicarboxylic acid) have been hydrothermally synthesized under different pH conditions, and characterized by IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Compound 1, formed at pH 5.4, contains two rare types of left-, right-handed [Cu-L]n helix chains, which are further connected by [Cu-1,4-chdc]n zigzag chains, affording a 2D wave-like polymeric network. Compound 2 was obtained at pH 5.9, and shows a 2D square-grid layer constructed from zigzag [Cu-L]n chains and linear [Cu-1,4-chdc]n chains. Compounds 3 and 4 possess a similar 2D grid layer to that of 2 with 44-sql topology, formed at pH 4.8 and 5.4 respectively, and are constructed from zigzag [Cu-L]n chains and linear [Cu-2,5-tdc]n chains. The effects of pH and secondary dicarboxylates on the diversity of structures are discussed. In addition, the thermal stabilities, photoluminescence properties, and photocatalytic activity of compounds 1–4 were also studied.