Browsing by Author "Bhupendra Kumar Dwivedi"

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AIE active piperazine appended naphthalimide-BODIPYs: photophysical properties and applications in live cell lysosomal tracking
(Royal Society of Chemistry, 2019) Bhupendra Kumar Dwivedi; Roop Shikha Singh; Afsar Ali; Vinay Sharma; Shaikh M. Mobin; Daya Shankar Pandey
Piperazine appended naphthalimide-BODIPYs (NPB1-NPB4) exhibiting solvatochromism and aggregation-induced emission with a large Stokes shift (up to 146 nm) have been described. Separation of naphthalimide and BODIPY fluorophores by piperazine in these conjugates creates a donor-acceptor system and induces twisted intramolecular charge transfer, in addition to photoinduced electron transfer. The crucial role of naphthalimide, the alkyl chain length, the piperazine ring, and the solid-state packing on AIE has been extensively investigated by various studies. Superior cell permeability coupled with bio-compatibility of these conjugates offers a unique opportunity for their potential applications in live cell lysosomal tracking. © The Royal Society of Chemistry.
Artificial light-harvesting systems (LHSs) based on boron-difluoride (BF2) hydrazone complexes (BODIHYs)
(Royal Society of Chemistry, 2021) Vishwa Deepak Singh; Bhupendra Kumar Dwivedi; Yogesh Kumar; Daya Shankar Pandey
In the quest to develop artificial light-harvesting systems (LHSs) with high energy transfer efficiency, hydrazone ligands L1-L2 and their -BF2 complexes (BODIHYs; B1 and B2) have been synthesized. Ligands L1 and L2 and the BODIHYs have been thoroughly characterized by various techniques (1H, 13C, 11B, and 19F NMR, ESI-MS, UV-vis and fluorescence). Further, the BODIHYs (B1 and B2) have been utilized as a new platform for artificial LHSs. It has been categorically shown that efficient artificial LHSs can be achieved by combining AIEgens B1 and B2 with rhodamine B (RhB) under aqueous conditions. In these systems B1 and B2 serve as a donor while RhB as an acceptor. The calculated energy transfer efficiency and antenna effect for the BODIHYs in combination with RhB came out to be appreciably high (B1 = 68%, 28.7; B2 = 80%, 35.5) at a donor/acceptor ratio of 25 : 1. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
BODIHY based novel AIEgens and directive role of σ–spacers on their reversible mechanochromism
(Elsevier Ltd, 2021) Vishwa Deepak Singh; Bhupendra Kumar Dwivedi; Yogesh Kumar; Daya Shankar Pandey
Synthesis of the novel hydrazone based ligands (L1–L3) and their borondifluoride (BF2) complexes (BODIHYs; B1–B3) have been described. The ligands and BODIHYs have been thoroughly characterized by spectroscopic studies (1H NMR, 13C NMR, 11B NMR, 19F NMR, ESI–MS, UV–vis and fluorescence) and structures of L1, L2 and B1–B3 determined by X–ray single crystal analyses. Emission behaviour of these compounds in solution and solid state have been fine tuned by varying the σ–spacers (–O, –S and –SO2). Vital role of various interactions in aggregation induced emission (AIE; B1 and B2), aggregation caused quenching (ACQ; B3) and reversible mechanochromism (B1–B3) have been rationalized by X-ray single crystal analyses. Dual emission band (~484 and 550 nm) for B3 have been attributed to the involvement of the intra-/and intermolecular charge transfer processes. The observed hypsochromic shift in these luminophores (upon grinding) successfully reverted back upon exposure to dichloromethane (CH2Cl2). An analysis of the powder X–ray diffraction (PXRD) pattern, before and after grinding advocated alteration of prevailing crystal packing by the external force as it rescinds the weak intra-/and intermolecular interactions of the molecule. © 2020 Elsevier Ltd
BODIPY-Based Multichromophoric Tripodal System as a Multifunctional Material
(American Chemical Society, 2022) Bhupendra Kumar Dwivedi; Ambikesh Dhar Dwivedi; Daya Shankar Pandey
The strategic design, synthesis, and thorough characterizations of a redox-active BODIPY-based tripodal system (tri-BDP) displaying efficient aggregation-induced emission (AIE), great sensitivity toward the viscosity of a medium, ability for triplet photosensitization, singlet oxygen generation, and photooxidation have been described. The photophysical properties of tri-BDP in various solvents and in the solid state have been extensively investigated. It displayed efficient AIE and green (∼520) emission in acetonitrile/ether mixture and red (∼621 nm) emission in the solid state. Detailed viscosity-dependent studies suggested that it can act as a fluorescent molecular rotor. Triplet photosensitization, singlet oxygen generation, and photooxidation studies in the presence of 1,3-diphenylisobenzofuran and 1,5-dihydroxyl naphthalene suggested its high efficiency toward intersystem crossing and singlet oxygen generation. Detailed electrochemical investigations suggested the redox activity of the system. Hence, this system represents multifunctional features and can be applied as a functional material for various applications. © 2022 American Chemical Society. All rights reserved.
Controlling Aggregation and Excited-State Intramolecular Proton Transfer in BODIPYs by Incorporation of 2-(2-Hydroxyphenyl)quinazoline and Variation of Substituents
(American Chemical Society, 2020) Bhupendra Kumar Dwivedi; Vishwa Deepak Singh; Rajendra Prasad Paitandi; Daya Shankar Pandey
A series of BODIPY-based AIEgens (QB1-QB5 and Bis-QB) containing 2-(2-hydroxyphenyl)quinazoline have been synthesized and thoroughly characterized. Photophysical properties of these compounds in solution and the aggregated state have been meticulously investigated and fine-tuned via structural modifications. These display green emission (∼530 nm) in solution and bright red emission (600-655 nm) in the aggregated/solid state with increased quantum yield. Crystal structure analyses and spectral studies revealed efficient J-type aggregation in these derivatives. Significant impact of 2-(2-hydroxyphenyl)quinazoline toward modulating intermolecular interactions and facilitating J-type stacking between BODIPY units has also been established. Moreover, the essential role of excited-state intramolecular proton transfer (ESIPT) in inducing emission in the aggregated state and tuning of ESIPT emission by variation of substituents have been supported by various studies. Copyright © 2020 American Chemical Society.
Controlling Photophysical Properties of Systems Containing Multiple BODIPY Units Linked by Methylene Bridge
(American Chemical Society, 2020) Bhupendra Kumar Dwivedi; Vishwa Deepak Singh; Daya Shankar Pandey
A series of tunable multicolor emitting AIEgens (B1-B8) with multiple BODIPY units linked by methylene and triazole bridges have been synthesized and thoroughly characterized. Close proximity of two symmetrical phenyl-BODIPY units in these systems enables them to display dual-emission band [λmax, ∼530 and ∼560 nm] due to monomer and excimer emission. These bands are sensitive to surroundings (concentration/temperature/solvent polarity) and can transform into single color emission (i.e., green to yellow and vice versa in solution while red in solid-state/dense medium). Triple-color (green, yellow, and red) emission for these derivatives can be achieved simply by changing concentration/viscosity of the mediums or by aggregation. Triple-color tunability has been achieved in solid poly(methyl methacrylate) films as well. Crystal structure analyses revealed nonplanar orientation with BODIPY units in close proximity. This arrangement ensures J-aggregation responsible for red emission in aggregated-/solid-state. Aggregation studies in DMSO/water mixture illustrated excellent aggregation-induced emission with large Stokes shift (up to 203 nm). © 2020 American Chemical Society.
Cyclometalated Ir(III) Complexes Involving Functionalized Terpyridine-Based Ligands Exhibiting Aggregation-Induced Emission and Their Potential Applications in CO2 Detection
(American Chemical Society, 2018) Vishwa Deepak Singh; Rajendra Prasad Paitandi; Bhupendra Kumar Dwivedi; Roop Shikha Singh; Daya Shankar Pandey
Synthesis of three novel terpyridine-based donor-acceptor (D-A) ligands (TP1, TP2, TP3) and cyclometalated iridium complexes [Ir(ppy)2TP1]+PF6 - (C1), [Ir(ppy)2TP2]+PF6 - (C2), and [Ir(ppy)2TP3]+PF6 - (C3) [ppy = 2-phenyl pyridine] involving these were described. The ligands and complexes were characterized by spectroscopic studies (1H, 13C, 19F, 31P, ESI-MS, UV-vis, and fluorescence). Crucial role of intermolecular interactions in aggregation-caused quenching (ACQ; C2) and aggregation-induced emission (AIE; C3) was rationalized by X-ray single-crystal analyses. Vital role of restricted intramolecular rotation (RIR) in inducing AIE upon aggregation via π-π interactions in these complexes was scrutinized by various studies. Because of strong intramolecular charge transfer these D-A based AIEgens exhibited solvatochromism. Further, AIE property of the complexes C1 and C3 was exploited toward detection of CO2. © 2018 American Chemical Society.
Effect of substituents on photophysical and aggregation behaviour in quinoline based bis-terpyridine Zn(II) complexes
(Elsevier S.A., 2019) Vishwa Deepak Singh; Bhupendra Kumar Dwivedi; Rajendra Prasad Paitandi; Yogesh Kumar; Daya Shankar Pandey
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, –CH3; C2 and –OCH3; 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 –CH3 (C2) and –OCH3 (C3) has been supported by DFT studies. © 2018 Elsevier B.V.
Intermolecular hydrogen bonding-assisted aggregation induced emission in quinolone-quinazoline conjugates and their potential use in acidochromism
(Royal Society of Chemistry, 2024) Irshad Ali; Bhupendra Kumar Dwivedi; Vishwa Deepak Singh; Daya Shankar Pandey
The effects of intermolecular hydrogen bonding on the aggregation behaviour for quinolone-quinazoline based D-A systems (Q1-Q3) have been reported. These compounds (Q1-Q3) have been strategically designed, synthesized and carefully characterized by spectral studies (IR, 1H, 13C-NMR, HRMS, UV/Vis, fluorescence) and their structures explicitly determined by X-ray single crystal analyses. Inclusion of apt electron donating groups (-H, Q1; -CH3, Q2 and -OCH3, Q3) enables these to display solvent-dependent emission indicative of a polarized excited state, probably due to enhanced intramolecular charge transfer (ICT). The occurrence of aggregation-induced emission enhancement (AIEE) in Q1-Q3 has been attributed to the restriction of the intramolecular rotation (RIR) and vibrations (RIV) via intermolecular hydrogen bonding. A possible role of the solvent and substituent in the photophysical behaviour and morphology of Q1-Q3 has been investigated by UV/Vis, emission, scanning electron microscopy (SEM) and dynamic light scattering (DLS) measurements. In addition, lowering of the energy gap between the HOMO and LUMO by electron donating substituents -CH3 (Q2) and -OCH3 (Q3) has been supported by DFT studies. Furthermore, they display reversible acid/base induced “ON-OFF-ON”-type signalling. The acidochromic behaviour upon exposure to acid/base has been supported by various studies. © 2024 The Royal Society of Chemistry.
Photophysical properties of some novel tetraphenylimidazole derived BODIPY based fluorescent molecular rotors
(Royal Society of Chemistry, 2020) Bhupendra Kumar Dwivedi; Vishwa Deepak Singh; Yogesh Kumar; Daya Shankar Pandey
The strategic design, synthesis and thorough characterization of four novel hydroxyl-substituted tetraphenylimidazole (HPI) based boron dipyrromethene (BODIPY) fluorophores (HPIB1-HPIB4) have been reported. Single crystal X-ray structure determination unveiled non-planar twisted orientations for these molecules. The non-planar orientations entirely restrict detrimental π-π interactions and avoid the non-radiative relaxation pathway for excited states in the solid/aggregated state and make them AIE active. The AIE characteristics of these compounds have been related to fine J-aggregation (evident from their crystal structures) along with restricted intra-molecular rotations (RIRs). These compounds display significant sensitivity toward viscosity and can serve as fluorescent molecular rotors due to multiple phenyl groups around the imidazole ring, which has been confirmed by measuring fluorescence quantum yields and lifetimes. © 2020 The Royal Society of Chemistry.
Photosensitization Ability of 1,7-Phenanthroline Based Bis-BODIPYs: Perplexing Role of Intramolecular Rotation on Photophysical Properties
(American Chemical Society, 2019) Vishwa Deepak Singh; Roop Shikha Singh; Bhupendra Kumar Dwivedi; Sujay Mukhopadhyay; Aparna Shukla; Pralay Maiti; Daya Shankar Pandey
1,7-Phenanthroline based bis-boron dipyrromethenes (bis-BODIPYs) B1 and B2 obtained via small substitutional changes (-Cl/-SCH3) have been described. The effect of restriction of intramolecular rotation (RIR) in emission enhancement in a viscous solvent (glycerol) has been studied besides the vital role of intermolecular interactions scrutinized by X-ray single-crystal studies. The efficiency of intersystem crossing (ISC) in the generation of singlet oxygen (φ ∼19.2% and 56.7%) by photoirradiation using visible light along with distinct photostability has been investigated by 1,3-diphenylisobenzofuran (DPBF) titration studies. The 1O2 generation quantum yield and photosensitizing durability of the bis-BODIPYs have been investigated by photooxidation of 1,5-dihydroxynaphthalene (DHN) in the presence of B1 and B2 as photosensitizers. The pseudo-first-order rate constants for photooxidation reactions and consumption rates of DHN reflected appreciable 1O2 generation quantum yields (φ: B1, 29.0; B2, 57.8%). Density functional theory (DFT) studies showed the distribution of electron density over the dipyrrin moiety. Overall results indicated that these new photosensitizers (PSs) may be very promising in photodynamic therapy of tumors, photobiology, and organic photochemistry. Copyright © 2019 American Chemical Society.
Piperazine appended naphthalimide-based organic scaffolds exhibiting efficient aggregation induced emission (AIE) and selective picric acid sensing
(Elsevier B.V., 2024) Ambikesh Dhar Dwivedi; Bhupendra Kumar Dwivedi; Mukta Tripathi; Daya Shankar Pandey
AIEgens (5a−5c & 6a−6c) derived from piperazine-appended naphthalimide have been synthesized via strategic modifications following multi-step process. Resulting compounds have been thoroughly characterized by spectroscopic techniques (IR, NMR (1H &13C), HRMS, UV/Vis and fluorescence spectroscopy). The compounds under study represent an asymmetric donor-acceptor (D-A) system with a D-A′-π-A construct. Expectedly, these display efficient aggregation-induced emission (AIE) which has been followed by UV/Vis, fluorescence, fluorescence lifetime and morphological (SEM) studies. Morphological studies on these systems revealed spherical nanostructures in aggregated state. These compounds display solid-state emission and solvatochromism. It has been observed that the donor unit plays a crucial role in directing photophysical properties including AIE. Moreover, synthesized compounds exhibited selective sensing toward picric acid. Further, DFT studies have been performed to support and co-relate the physical properties. © 2024
Pyrazole appended quinoline-BODIPY based arene ruthenium complexes: their anticancer activity and potential applications in cellular imaging
(Royal Society of Chemistry, 2018) Rajendra Prasad Paitandi; Vinay Sharma; Vishwa Deepak Singh; Bhupendra Kumar Dwivedi; Shaikh M. Mobin; Daya Shankar Pandey
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. © The Royal Society of Chemistry.
Red-emissive quinoxaline-based BODIHY: Aggregation-induced emission and multi-responsive properties
(Elsevier Ltd, 2024) Bhupendra Kumar Dwivedi; Prasanta Bhowmik; Sunil Kumar Pandey; Daya Shankar Pandey
Two new BODIHY-based AIEgens DQB1 and DQB2 including quinoxaline and benzothiazole scaffold have been synthesized and characterized. Comprehensive photophysical properties of the compounds in solution and aggregated/solid state have been investigated and fine-tuned via structural modifications. These display quite high Stokes shift (≥5991 cm−1) in solution and aggregated/solid state. Further, these derivatives display faint emission in solution (THF), while bright yellow [λem; 560 nm (DQB1)] and intense red [λem; ∼650 nm (DQB2)] in aggregated state with good quantum yield [Φf; 17.5 (DQB1) and 23.2 (DQB2)], and represent a family of dye with good AIE characteristics. Both the systems display superior solid state emission and crystallization-induced red-shifted emission. It has been shown that the compounds under study exhibit multi-responsive characteristics toward external stimuli, particularly significant color tuning in solid state due to mechanical stress and acid/base vapors. Crystal structure analyses for both DQB1 and DQB2 revealed efficient J-type aggregation and vital role of the intermolecular interactions toward AIE and multi-responsive properties. © 2024
Solid state emissive azo-Schiff base ligands and their Zn(ii) complexes: Acidochromism and photoswitching behaviour
(Royal Society of Chemistry, 2021) Yogesh Kumar; Vishwa Deepak Singh; Bhupendra Kumar Dwivedi; Nikhil Kumar Singh; Daya Shankar Pandey
The synthesis of Zn(ii) complexes (C1-C2) based on azo-Schiff base ligands 2-((E)-(phenyl-imino)methyl)-4-((E)-(2-(phenylthio)phenyl)diazenyl)phenol (L1) and 4-((E)-(2-(phenyl-thio)phenyl)diazenyl)-2-((E)-(p-tolylimino)methyl)phenol (L2) has been described. These have been thoroughly characterized by spectroscopic studies (IR, 1H, 13C, ESI-MS, electronic absorption, emission) and the structures of C1 and C2 have been determined by X-ray single crystal analyses. The ligands L1 and L2 exhibit reversible acid/base induced "ON-OFF-ON"switching in solution and solid state. Upon exposure to UV light (λ, 365 nm) C1 and C2 display cis-trans photoisomerisation and after removal of light they transform to more stable trans-form. Electronic absorption and 1H NMR studies on C1 and C2 revealed rather rapid (1.27 × 10-1 s-1) photoisomerization for C2 relative to C1 (2.7 × 10-2 s-1) which has also been supported by theoretical studies (DFT). The rather fast photoisomerization for C2 compared to C1 may be related to a small energy gap between HOMO and LUMO levels for the respective isomers. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Solvent-Dependent Self-Assembly and Aggregation-Induced Emission in Zn(II) Complexes Containing Phenothiazine-Based Terpyridine Ligand and Its Efficacy in Pyrophosphate Sensing
(American Chemical Society, 2018) Vishwa Deepak Singh; Roop Shikha Singh; Rajendra Prasad Paitandi; Bhupendra Kumar Dwivedi; Biswajit Maiti; Daya Shankar Pandey
Zn(II) complexes MTPY-ZnCl2 (C1) and MTPY-Zn(NO3)2 (C2) based on a new D-A type ligand MTPY involving phenothiazine donor and terpyridine acceptor units have been described. The ligand MTPY and complexes C1 and C2 display intramolecular charge transfer and substantial solvatochromism. Solid-state emission studies on MTPY further substantiated the occurrence of concentration-induced emission in this molecule. In addition, the complexes C1 and C2 displayed a solvent-dependent self-assembly which has been examined as a function of the hydrophilic and hydrophobic nature of the solvent systems. The role of hydrophilicity/hydrophobicity of a solvent and compounds on morphology and emission characteristics of the self-assembled aggregates has been investigated by UV-vis, emission, and scanning electron microscopy studies. In addition, it has been categorically shown that aggregation-induced emission in C1 offers a simple, sensitive, and rapid means for the detection of pyrophosphates (PPi) in the aqueous medium. Job's plot analysis suggested a 3:1 binding stoichiometry between C1 and PPi, which has been supported by electrospray ionization mass spectrometry and density functional theory. Further, higher affinity of PPi toward C1 over C2 has also been rationalized by theoretical studies. © 2018 American Chemical Society.
Substituent-directed ESIPT-coupled Aggregation-induced Emission in Near-infrared-emitting Quinazoline Derivatives
(Wiley-VCH Verlag, 2018) Bhupendra Kumar Dwivedi; Vishwa Deepak Singh; Rajendra Prasad Paitandi; Daya Shankar Pandey
A series of ESIPT (excited state intramolecular proton transfer) active systems (HQz1–HQz6) derived from quinazoline have been reported. The ESIPT emission for these derivatives gets completely quenched in solvents with diverse polarities which have been restored via aggregation-induced emission (AIE) with large Stokes shift (up to 314 nm). It varied from 450 to 701 nm just by altering substituents at the para position of hydroxy group in the central phenyl ring. As well, HQz1–HQz6 displayed solid state emission [∼455 (blue) to ∼704 nm (red)]. The formyl group on the central hydroxy-phenyl ring of these derivatives induces ESIPT by increasing acidity of the hydroxy proton which has been followed by 1H NMR studies. Further, it has been clearly shown that emission colour and aggregate morphology can be fine tuned by incorporating apt substituents. The present study offers a simple route to obtain colour tunable ESIPT emission via AIE which is very important for biological imaging and fabrication of optoelectronic devices. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Substituent-modulated aggregation-induced emission and solid-state acid/base sensing applications of pyrazole-based donor-acceptor derivatives
(Elsevier Ltd, 2022) Bhupendra Kumar Dwivedi; Prasanta Bhowmik; Daya Shankar Pandey
AIE-active luminophores (PYZ1−PYZ4) containing substituted pyrazole as a donor and cyanomethylene/benzothiazole as acceptor units have been synthesized and thoroughly characterized by IR, 1H/13C NMR, HRMS and single crystal X-ray diffraction analyses. These new systems exhibited efficient aggregation induced emission and solid-state emission with good quantum yield. Interestingly, these compounds display acid/base-induced reversible solid-state fluorescence switching, and could be used as a solid-state acid/base sensor. Structure-property relationship investigations clearly showed that structural changes strongly influence photophysical properties of these compounds. © 2022
Time dependent aggregation induced emission enhancement and the study of molecular packing in closely related azo-phenol BODIPY species
(Royal Society of Chemistry, 2018) Rajendra Prasad Paitandi; Roop Shikha Singh; Bhupendra Kumar Dwivedi; Vishwa Deepak Singh; Daya Shankar Pandey
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. © 2018 The Royal Society of Chemistry.