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Semiconducting covalent organic frameworks (COFs) are emerging materials for the photocatalytic hydrogen (H2) evolution, owing to their porous periodic network of π-conjugated scaffolds with tuneable band gap and optoelectronic properties. The optoelectronic properties, for example, band gap, band position and charge carrier mobility of the COF photocatalyst, play a pivotal role in their activity in photocatalytic conversions. However, it is challenging to control the band gap and band position of COFs simultaneously. In the present manuscript, we investigate the photocatalytic performance of low band gap semiconducting COFs constructed from anthracene containing π-conjugated building blocks linked with different hydroxy functionalized 1,3,5-triformylbenzene. Along with crystalline and porous COF powders, thin COF films were synthesized successfully. Such thin COF films offer several advantages in photocatalytic applications owing to their low light scattering, scalability and reusability. It is furthermore shown that the number of hydroxy groups on the 1,3,5-triformylbenzene linker largely influences the properties of the final COFs. The COF prepared from the linker with two hydroxy groups exhibits the lowest band gap of 1.8 eV and efficient exciton migration due to the formation of J-type aggregates resulting in the maximum hydrogen evolution rate (8.4 ± 0.5 mmol g−1 h−1) in the powder state. On the other hand, for COF films a steady increase in hydrogen evolution rate is observed with increasing hydroxy-functionalization and reaches a maximum for three hydroxy groups (1.6 ± 0.2 mmol m−2 h−1) due to the enhanced charge carrier mobility. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have emerged as ideal multifunctional platforms for renewable hydrogen (H2) energy applications owing to their tunable chemical compositions and structures and high porosity. Their advanced component species and porous structure contribute greatly to the enhanced activity, electrical conductivity, photo response, charge‐hole separation efficiency, and structural stability of MOF materials, which are promising for practical H2 economy. In this review, we mainly introduce design strategies for the enhancement of electro‐/photochemical behaviors or adsorption performance of porous MOF materials for H2 production, storage, and utilization from compositional perspective. Following these engineering strategies, the correlation between composition and property‐structure‐performance of pristine MOFs and their composite with advanced components is illustrated. Finally, challenges and directions of future development of related MOFs and MOF composites for H2 economy are provided. [ABSTRACT FROM AUTHOR]

Synthesis of an entirely new series of arene ruthenium complexes [Ru(η6-C6H6)(L1)Cl]PF6, (1), [Ru(η6-C10H14)(L1)Cl]PF6 (2), [Ru(η6-C6H6)(L2)Cl]PF6 (3) and [Ru(η6-C10H14)(L2)Cl]PF6 (4) involving 5-[2-(1H-pyrazol-1-yl)quinoline]-BODIPY (L1) and 5-[6-methoxy-2-(1H-pyrazol-1-yl)quinoline]-BODIPY (L2) was described. The ligands and complexes were thoroughly characterized by various physicochemical techniques and the structures of L1, 1 and 4 were determined by X-ray single crystal analyses. Photo-/ and electrochemical property, DNA binding, cytotoxicity, cellular uptake and apoptotic studies on 1–4 were performed by various methods, while singlet oxygen-mediated cytotoxicity via photo-irradiation by visible light was supported by 1,3-diphenylisobenzofuran titration studies. Binding of the complexes in the minor groove of CT-DNA via van der Waals forces and electrostatic interactions was affirmed by molecular docking studies. In vitro antiproliferative activity and photocytotoxicity of 1–4 were examined against the human cervical cancer cell line (HeLa) which clearly showed that these are extremely photocytotoxic under visible light (400–700 nm, 10 J cm−2; IC50 49.15, 1; 25.18, 2; 15.85, 3; 12.87, 4), less toxic in the dark (IC50 ＞ 100 μM) and preferentially accumulate in the lysosome of the HeLa cells. Further, these complexes behave as a potential theranostic agent and their ability to kill cancer cells under visible light lies in the order 4 ＞ 3 ＞ 2 ＞ 1. [ABSTRACT FROM AUTHOR]

Fluorescent azo-phenol BODIPYs (1–3) have been obtained by the substituent (–OCH3/–CH3) directed synthesis of ortho (L1) and para (L2–L3) azo-phenol aldehydes. These display aggregation caused quenching (ACQ, 1) and aggregation induced emission enhancement (AIEE, 2 and 3) depending on the position of azo relative to the phenolic hydroxyl group. An intriguing time dependent morphological transition from nanospheres to ordered nanorods and subsequent emission changes in AIEE active azo-phenol BODIPYs have been successfully realized by time dependent fluorescence, scanning electron (SEM), transmission electron (TEM) and fluorescence optical microscopy (FOM) studies. The existence of one-dimensional (1D) nanorods as ultimate species in these compounds (2–3) has been supported by crystal packing patterns. Diverse aggregated forms and hierarchical nanostructures have been related to variable extents of fluorescence enhancement. The plausible charge transfer process and its role in AIEE have been supported by DFT studies. [ABSTRACT FROM AUTHOR]

Synthesis of terpyridyl based ligands 3-([2,2′:6′,2′′-terpyridin]-4′-yl)-7-methoxy-2-(methylthio)-quinolone, (L1); 3-([2,2′:6′,2′′-terpyridin]-4′-yl)-6-methoxyquinolin-2(1H)-one, (L2); 3-([2,2′-:6′,2′′-terpyridin]-4′-yl)-6-methylquinolin-2(1H)-one (L3) and cyclometalated iridium(iii) complexes [[Ir(ppy)2L1]+PF6− (1), [Ir(ppy)2L2]+PF6− (2), [Ir(ppy)2L3]+PF6− (3) (2-phenylpyridine = Hppy)] involving these ligands has been described. The ligands L1–L3 and complexes 1–3 have been thoroughly characterized by elemental analyses, spectral studies (IR, 1H, 13C NMR, UV/vis and fluorescence) ESI-MS, and the structure of 3 has been unambiguously authenticated by single crystal X-ray analyses. UV/vis, fluorescence and circular dichroism spectroscopic studies showed rather efficient binding of 1 with CT-DNA (calf thymus DNA) and BSA (bovine serum albumin) relative to 2 and 3. Molecular docking studies unveiled binding of 1–3 with minor groove of CT-DNA via van der Waal's forces and electrostatically with the hydrophobic moiety of HSA (human serum albumin). The ligands and complexes exhibited moderate cytotoxicity towards MDA-MB-231 (breast cancer cell line) and significant influence on HeLa (cervical cancer cell line) cells. Cytotoxicity, morphological changes, and apoptosis have been followed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay, Hoechst 33342/PI (PI = propidium iodide) staining, cell cycle analysis by FACS (fluorescence activated cell sorting), and ROS (reactive oxygen species) generation by DCFH-DA (dichlorodihydrofluorescein diacetate) dye. Confocal microscopy images revealed that the drug efficiently initiates apoptosis in the cell cytosol. The IC50 values showed superior cytotoxicity of 1–3 against the HeLa cell line relative to cisplatin, and their ability to induce apoptosis is in the order 1 ＞ 2 ＞ 3. [ABSTRACT FROM AUTHOR]

A series of copper(ii) complexes (1–9 and 3′) derived from bis-dipyrrin ligands (L1–L9 and L3′) with diverse spacer lengths [–(CH2)n–] have been described. Structural diversities in these complexes have been explicitly established by spectral and structural studies on these and a closely related nickel(ii) complex (3′′). All the ligands and complexes have been thoroughly characterized by spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV/vis) and structures of 2, 3′, 3′′, 6, 8 and 9 were determined by X-ray single crystal analyses. It has been unambiguously established that ligands with n≤ 6 gave heteroleptic binuclear (1–5), while those with n≥ 7 yielded homoleptic mononuclear (6–9) bis-dipyrrinato complexes. Spectral and structural studies revealed distorted square planar (1–5) and distorted tetrahedral geometries (6–9) about the copper(ii) centre in these complexes which has further been evidenced by EPR and electrochemical studies. Structural differences based on the odd and even number of methylene spacers in these complexes have been supported by DFT studies. A line between the syn- and anti-conformations of the complexes has been drawn on the basis of a limiting spacer length. [ABSTRACT FROM AUTHOR]

Synthesis of four new arene ruthenium(II) complexes [(η 6 -C 10 H 14 )RuCl(MFPdpm)] ( 1 ); [(η 6 -C 12 H 18 )Ru-Cl(MFPdpm)] ( 2 ); [(η 6 -C 10 H 14 )RuCl(PFPdpm)] ( 3 ) and [(η 6 -C 12 H 18 )RuCl(PFPdpm)] ( 4 ) containing dipyrrin ligands 5-(4-fluoro)phenyldipyrromethene (MFPdpm) and 5-(penta-fluoro)phenyldipyrromethene (PFPdpm) have been described. The ligands and complexes have been thoroughly characterized by elemental analyses, spectroscopic studies (ESI-MS, IR, 1 H, 13 C NMR, UV–Vis) and structure of the representative complex 4 determined by X-ray single crystal analyses. DNA binding activities of 1 – 4 have been investigated by UV–Vis and fluorescence spectroscopy and their binding through the minor groove of DNA has been established by molecular docking studies. The complexes 1 – 4 exhibit significant cytotoxicity toward human lung cancer cell line (A549). Cytotoxicity, morphological changes, and apoptosis studies have been evaluated through MTT assay, Hoechst 33342/PI staining, and cell cycle analysis by fluorescence activated cell sorting (FACS). In vitro antitumor activity and cytotoxicity of the complexes lie in the order 4 > 3 > 2 > 1 . [ABSTRACT FROM AUTHOR]

Four organometallic complexes [(η6-C6H6)RuCl(pmpzdpm)], 1; [(η6-C6H6)RuCl(pypzdpm)], 2; [(η6-C10H14)RuCl(pmpzdpm)], 3 and [(η6-C10H14)RuCl(pypzdpm)], 4 containing 5-(2-pyrimidyl-piperazine)phenyldipyrromethene (pmpzdpm) and 5-(2-pyridylpiperazine)phenyldipyrromethene (pypzdpm) have been designed and synthesized. The complexes 1–4 have been fully characterized by elemental analyses and spectroscopic studies (ESI-MS, IR, 1H, 13C NMR, UV–vis). Their electrostatic/intercalative interaction with CT DNA has been investigated by UV–vis and competitive ethidium bromide displacement studies while their protein binding affinity toward bovine serum albumin (BSA) was realized by UV–vis, fluorescence, synchronous and three dimensional (3D) fluorescence studies. The interaction with DNA and protein has further been validated by in silico studies. Cellular uptake, in vitro cytotoxicity and flow cytometric analyses have been performed to determine the mode of cell death against the kidney cancer cell line ACHN. Cell cycle analysis suggested that the complexes cause cell cycle arrest in the subG1 phase and overall results indicated that the in vitro antitumor activity of 1–4 lies in the order of 3 ＞ 4 ＞ 1 ＞ 2 (IC50, 7.0 1; 8.0 2; 2.0 3; 4.0 μM, 4). [ABSTRACT FROM AUTHOR]

With intent to fine tune the morphological and photophysical properties, three novel AIE luminogens (BQ1–BQ3) based on quinoline–BODIPY have been synthesized. A judicious choice of substituents (–H, –CH3, –OCH3) in these systems led to nanoballs in BQ1 and BQ2, while in BQ3 it led to reticulated nanofibers with diverse photophysical behaviours. [ABSTRACT FROM AUTHOR]

An expeditious synthesis of new click reaction-based BODIPY–piperazine conjugates separated by alkyl spacers (4–7) has been described. The compounds under investigation have been thoroughly characterized by various physicochemical techniques viz., elemental analyses, IR, HRMS, NMR (1H, 13C, 11B and 19F), electronic absorption, emission and theoretical studies. The comparative sensing abilities of 4–7 toward a range of metal ions have been investigated by various methods. Among these compounds, only 7 exhibited appreciable selectivity towards Hg2+, while the others remained inactive in the presence of various metal ions. Binding constant and Job's plot analysis indicated 1 : 1 stoichiometry between 7 and Hg2+. HRMS data and theoretical studies undoubtedly indicated the formation of a 7·Hg2+ complex and interaction of Hg2+ with the probe via nitrogen atoms in the piperazine and triazole units. [ABSTRACT FROM AUTHOR]

Graphical abstract Three push-pull type terpyridine ligands (L1 – L3) based Zn(II) complexes (C1 – C3) have been synthesized and their photophysical properties thoroughly examined. The role of substituents (–H, C1 ; –CH3, C2 and –OCH3, C3) and solvent on photophysical behaviour and morphology of aggregate (C3) have been established with the help of various spectroscopic studies (UV/Vis, fluorescence and SEM). Abstract Synthesis of the terpyridine based novel Zn(II) complexes (C1 – C3) have been described. Characterization of these complexes has been achieved by spectroscopic studies (IR, 1H, 13C, 19F, HRMS, UV/Vis and fluorescence) and structure of C1 determined by X-ray single crystal analyses. Cautious tuning by incorporating appropriate substituents (–H; C1 , –CH 3 ; C2 and –OCH 3 ; C3) enabled the complexes to exhibit solvent dependent emission indicative of more polarized excited state probably due to enhanced intramolecular charge transfer (ICT). Occurrence of aggregation induced emission (AIE) in C3 has been validated by solid state emission and vital role of RIR in inducing AIE upon aggregation by fluorescence lifetime experiments. The role of solvent and substituents on photophysical behaviour and morphology of the complexes has been investigated by UV/Vis, emission and scanning electron microscopy (SEM). As well, lowering of the energy gap between HOMO and LUMO by electron donating substituents –CH 3 (C2) and –OCH 3 (C3) has been supported by DFT studies. [ABSTRACT FROM AUTHOR]

Synthesis of terpyridyl based ligands 3-([2,2':6',2''-terpyridin]-4'-yl)-7-methoxy-2-(methylthio)-quinolone, (L1); 3-([2,2':6',2''-terpyridin]-4'-yl)-6-methoxyquinolin-2(1H)-one, (L2); 3-([2,2'-:6',2''-terpyridin]-4'-yl)-6-methylquinolin-2(1H)-one (L3) and cyclometalated iridium(iii) complexes [[Ir(ppy) 2 L1] + PF 6 - (1), [Ir(ppy) 2 L2] + PF 6 - (2), [Ir(ppy) 2 L3] + PF 6 - (3) (2-phenylpyridine = Hppy)] involving these ligands has been described. The ligands L1-L3 and complexes 1-3 have been thoroughly characterized by elemental analyses, spectral studies (IR, 1 H, 13 C NMR, UV/vis and fluorescence) ESI-MS, and the structure of 3 has been unambiguously authenticated by single crystal X-ray analyses. UV/vis, fluorescence and circular dichroism spectroscopic studies showed rather efficient binding of 1 with CT-DNA (calf thymus DNA) and BSA (bovine serum albumin) relative to 2 and 3. Molecular docking studies unveiled binding of 1-3 with minor groove of CT-DNA via van der Waal's forces and electrostatically with the hydrophobic moiety of HSA (human serum albumin). The ligands and complexes exhibited moderate cytotoxicity towards MDA-MB-231 (breast cancer cell line) and significant influence on HeLa (cervical cancer cell line) cells. Cytotoxicity, morphological changes, and apoptosis have been followed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide) assay, Hoechst 33342/PI (PI = propidium iodide) staining, cell cycle analysis by FACS (fluorescence activated cell sorting), and ROS (reactive oxygen species) generation by DCFH-DA (dichlorodihydrofluorescein diacetate) dye. Confocal microscopy images revealed that the drug efficiently initiates apoptosis in the cell cytosol. The IC 50 values showed superior cytotoxicity of 1-3 against the HeLa cell line relative to cisplatin, and their ability to induce apoptosis is in the order 1 > 2 > 3.

Four organometallic complexes [(η(6)-C6H6)RuCl(pmpzdpm)], 1; [(η(6)-C6H6)RuCl(pypzdpm)], 2; [(η(6)-C10H14)RuCl(pmpzdpm)], 3 and [(η(6)-C10H14)RuCl(pypzdpm)], 4 containing 5-(2-pyrimidyl-piperazine)phenyldipyrromethene (pmpzdpm) and 5-(2-pyridylpiperazine)phenyldipyrromethene (pypzdpm) have been designed and synthesized. The complexes 1-4 have been fully characterized by elemental analyses and spectroscopic studies (ESI-MS, IR, (1)H, (13)C NMR, UV-vis). Their electrostatic/intercalative interaction with CT DNA has been investigated by UV-vis and competitive ethidium bromide displacement studies while their protein binding affinity toward bovine serum albumin (BSA) was realized by UV-vis, fluorescence, synchronous and three dimensional (3D) fluorescence studies. The interaction with DNA and protein has further been validated by in silico studies. Cellular uptake, in vitro cytotoxicity and flow cytometric analyses have been performed to determine the mode of cell death against the kidney cancer cell line ACHN. Cell cycle analysis suggested that the complexes cause cell cycle arrest in the subG1 phase and overall results indicated that the in vitro antitumor activity of 1-4 lies in the order of 3 >4 >1 >2 (IC50, 7.0 1; 8.0 2; 2.0 3; 4.0 μM,4 ).