Energy Transfer Pathways Research Articles

Time-resolved Fluorescence Spectroscopy Study of Energy Transfer Dynamics in Phycobilisome of Thermophilic Cyanobacterium Thermosynechococcus vulcanus NIES 2134

Phycobilisomes (PBSs) are the largest light-harvesting complex in cyanobacteria and red algae. To understand the energy transfer dynamics in phycobilisome, the cyanobacterium, Thermosynechococcus vulcanus NIES 2134 (T. 2134), with a phycocyanin (PC) trimer PC612 linking the rod and core, was selected. The energy transfer dynamics in PBS from T. 2134 were studied via time-resolved fluorescence spectroscopy in sub-picosecond resolution. The energy transfer pathways and transfer rates were uncovered by deconvolution of the fluorescence decay curve. A fast time-component of 10 ps from PC612 trimer to the core and a slow time-component of 80 ps from rods to the core were recognized in the energy transfer in PBSs. The faster energy transfer rate of 10 ps enables PC612 trimer to modulate the energy transfer dynamics between rods and core. The findings help us understand the structure-induced energy transfer mechanisms in PBSs.

Crystal growth and visible fluorescence and energy transfer features of Dy3+/RE3+ (RE = Tb, Eu)-codoped Y3Al5O12 crystals

In this work, 4 at% Dy3+: YAG (Dy: YAG), 4 at% Dy3+/0.5 at% Tb: YAG (Dy/Tb: YAG), 4 at% Dy3+/0.5 at% Eu3+: YAG (Dy/Eu: YAG), 0.5 at% Tb: YAG (Tb: YAG), and 0.5 at% Eu3+: YAG (Eu: YAG) crystals have been synthesized by the Czochralski method. Optical absorption and luminescence spectra of Dy: YAG, Dy/Tb: YAG, and Dy/Eu: YAG crystals are contrasted and discussed. Through emission decay times of Dy3+: 4F9/2 level in related crystals and the fluorescence spectra under different excitations, the energy transfer pathways between Dy3+ and Tb3+, and Dy3+ and Eu3+ ions are explored. Additionally, Judd-Ofelt analysis is performed to estimate distinct spectroscopic factors like radiative transition rates, fluorescence branching ratios, and radiative lifetimes.

Crystal structure analysis of phycoerythrin from marine cyanobacterium Halomicronema

Phycoerythrin (PE) is green light-absorbing pigment-protein that assists in efficient light harvesting in cyanobacteria and red-algae. PE in cyanobacteria stays less studied so far as compared to that in red algae. In this study, PE from marine cyanobacteria Halomicronema sp. R31DM is purified and subjected for its structural characterisation by X-ray crystallography in order to understand its light-harvesting characteristics. The crystal structure is solved to a resolution-limit of 2.21 Å with reasonable R-factors values, 0.16/0.21 (Rwork/ Rfree). PE forms hexamer of hetero-dimers made up of two peptide chains, α- and β-subunits containing 2 and 3 phycoerythrobilin (PEB) chromophores covalently attached to them, respectively. Geometry of five chromophores is analysed along with their relative position within the PE hexamer. Also, their interactions with the surrounding microenvironment are analysed. The plausible energy transfer pathways in hexamer structure have been predicted based on relative position and geometry of chromophores. This structure enriches the structural information of cyanobacterial PE in order to understand its light-harvesting capacity. Communicated by Ramaswamy H. Sarma

Manganese Ion‐Sensitized Near‐Infrared Light in Cs2NaBi1−xErxCl6 Lead‐Free Double Perovskite

AbstractLead‐free double perovskites (DPs) with unique optical properties are of interest for broad applications. However, improving near‐infrared (NIR) photoluminescence (PL) in lead‐free DPs is still a challenge. Herein, in order to increase the NIR PL intensity and extend the infrared multicolor luminescence, transition metal Mn2+ is doped into Cs2NaBi1−xErxCl6 lead‐free DPs. Steady‐state and time‐resolved PL studies show that efficient energy transfer from Mn2+ to Er3+ is obtained, leading to NIR PL at ≈1.54 µm can be enhanced 11‐fold compared to Er3+ singly alloyed sample and a PL quantum yield of ≈14.2%. Moreover, the Mn2+‐mediated sensitized strategy can expand to other NIR lanthanide ions (Ho3+ at ≈0.98 µm or Nd3+ at ≈1.07 µm). The as‐synthesized Mn2+ doped Cs2NaBi1−xErxCl6 DPs exhibit robust stability against heat, ultraviolet light, and environmental oxygen/moisture. Finally, the lead‐free DPs phosphor‐converted multifunctional white light‐emitting diode device containing visible and NIR light is fabricated. This work guides constructing energy transfer pathways in DPs and opens new perspectives for the development of lanthanide‐functionalized DPs as promising materials for optoelectronic devices operating in the NIR region.

Optical and photophysical portrayal of Sm3+ complexes possessing two band gaps for relevance in solar cells and photovoltaic devices

Octa-coordinated samarium (III) complexes were synthesised using a fluorinated β-keto carboxylic acid (L) as prime ligand and N-donor systems as auxillary ligands, by ecologically desirable grinding method. The photoluminescent properties were investigated in powder and solution form. The characteristic emission at ∼605 nm (solid state) and ∼599 (solution phase) relative to 4G5/2 → 6H7/2 transition is accountable for the bright vermillion color of complexes. Quantum yield and colorimetric parameters were obtained for solid and solution state. CCT and color purity value characterise these complexes as warm orange light source. Reflectance spectra of solid complexes were fitted nonlinearly to procure optical band gap and Urbach band tail width. Two band gaps were reported in each complex, hence can have materiality in solar cell and photovoltaic devices. The FWHM obtained for most emissive transition (4G5/2 → 6H7/2) is found to be comparable with Nd-doped fluorophosphates glass. Energy transfer pathway studied for all the synthesised complexes, affirmed the effective energy transfer from ligands to Sm3+ ion. Investigation of antimicrobial behaviour of complexes revealed either higher or similar activity with respect to the ligand.

Energy transfer fluctuation observed by single-molecule spectroscopy of red-shifted bacteriochlorophyll in the homodimeric photosynthetic reaction center.

The photosynthetic reaction center of heliobacteria (hRC) is a homodimeric chromoprotein responsible for light harvesting and photoelectric conversion. The fluorescence of the hRC is radiated from a bacteriochlorophyll (Bchl) g having the lowest energy level, called red-Bchl g. The homodimeric architecture of the hRC indicates that it includes two red-Bchls g arranged symmetrically in pairs. Red-Bchl g is a fluorescent probe useful for monitoring the energy transfer network in the RC. Here, we show the fluorescence polarization dependences of two red-Bchls g, individually measured with selective excitation of chlorophyll a serving as the primary electron acceptor. The two red-Bchls g exhibit almost the same polarization dependences. Based on the polarization dependence and structural data of the hRC, we propose a candidate molecule for red-Bchl g. The fluorescence spectra of single hRCs represent the spectral heterogeneity reflecting the local conformational inhomogeneity. A time series of the fluorescence spectra indicates occasional peak shifts between blue- and red-shifted states without significant changes in the fluorescence intensity. The spectral fluctuation is interpreted to be due to the local conformational dynamics around a Bchl g mediating the energy transfer, switching the terminal energy acceptor between two red-Bchls g. In conclusion, while the energy transfer network in the RC can be perturbed by microscopic dynamics, the total energy transfer efficiency, i.e., the light-harvesting function, is rather robust. The functional robustness may be due to multiple energy transfer pathways composed of many antenna pigments in the RC.

Vinylcyclopropane [3+2] Cycloaddition with Acetylenic Sulfones Based on Visible Light Photocatalysis.

The first intermolecular visible light [3+2] cycloaddition reaction performed on a meta photocycloadduct employing acetylenic sulfones is described. The developed methodology exploits the advantages of combining UV and visible‐light in a two‐step sequence that provides a photogenerated cyclopropane which, through a strain‐release process, generates a new cyclopentane ring while significantly increasing the molecular complexity. Mechanistic studies and DFT calculations indicate an energy transfer pathway for the visible light‐driven reaction step. This strategy could be extended to simpler vinylcyclopropanes.

BODIPY-Based Polymers of Intrinsic Microporosity for the Photocatalytic Detoxification of a Chemical Threat.

Effective heterogeneous photocatalysts capable of detoxifying chemical threats in practical settings must exhibit outstanding device integrity. We report a copolymerization that yields robust, porous, processible, chromophoric BODIPY (BDP; boron-dipyrromethene)-containing polymers of intrinsic microporosity (BDP-PIMs). Installation of a pentafluorophenyl at the meso position of a BDP produced reactive monomer that when combined with 5,5,6,6-tetrahydroxy-3,3,3,3-tetramethyl-1,1-spirobisindane (TTSBI) and tetrafluoroterephthalonitrile (TFTPN) yields PIM-1. Postsynthetic modification of these polymers yields Br-BDP-PIM-1a and -1b─polymers containing bromine at the 2,6-positions. Remarkably, the brominated polymers display porosity and processability features similar to those of H-BDP-PIMs. Gas adsorption reveals molecular-scale porosity and Brunette-Emmet-Teller surface areas as high as 680 m2 g-1. Electronic absorption spectra reveal charge-transfer (CT) bands centered at 660 nm, while bands arising from local excitations, LE, of BDP and TFTPN units are at 530 and 430 nm, respectively. Fluorescence spectra of the polymers reveal a Förster resonance energy-transfer (FRET) pathway to BDP units when TFTPN units are excited at 430 nm; weak phosphorescence at room temperature indicates a singlet-to-triplet intersystem crossing. The low-lying triplet state is well positioned energetically to sensitize the conversion of ground-state (triplet) molecular oxygen to electronically excited singlet oxygen. Photosensitization capabilities of these polymers toward singlet-oxygen-driven detoxification of a sulfur-mustard simulant 2-chloroethyl ethyl sulfide (CEES) have been examined. While excitation of CT and LEBDP bands yields weak catalytic activity (t1/2 > 15 min), excitation to higher energy states of TFTPN induces significant increases in photoactivity (t1/2 ≅ 5 min). The increase is attributable to (i) enhanced light collection, (ii) FRET between TFTPN and BDP, (iii) the presence of heavy atoms (bromine) having large spin-orbit coupling energies that can facilitate intersystem crossing from donor-acceptor CT-, FRET-, or LE-generated BDP singlet states to BDP-related triplet states, and (iv) polymer triplet excited-state sensitization of the formation of CEES-reactive, singlet oxygen.

Embedding an organic dye into Ti-MCM-48 for direct photocatalytic selective aerobic oxidation of sulfides driven by green light

Ti-containing mesoporous silica materials with a well-defined structure could give a clear picture of the elusive reaction pathways in photocatalysis. However, the dispersion of Ti sites usually results in their bandgaps being larger than that of TiO2, which makes the narrowing of bandgaps more challenging to construct visible light photocatalysis. Here, Ti-MCM-48 with an ordered cubic mesostructure and a homogeneous dispersion of Ti sites were successfully synthesized to embed an organic dye alizarin red S (ARS), affording a visible light photocatalyst ARS–Ti-MCM-48. The selective aerobic oxidation of sulfides into sulfoxides driven by green light over ARS–Ti-MCM-48 was accomplished directly. Notably, both electron transfer and energy transfer pathways were involved in the activation of O2, in which the Ti sites play a crucial role. Importantly, the photobleaching was effectively alleviated by embedding ARS into the mesopores of Ti-MCM-48. Moreover, high selectivities of desired sulfoxides were favorably achieved. In general, Ti-containing porous materials could be a unique scaffold for embedding photoactive molecules to carry out selective organic transformations driven by visible light.

Understanding the characteristics of non-equilibrium alternating current gliding arc discharge in a variety of gas mixtures (air, N2, Ar, Ar/O2, and Ar/CH4) at elevated pressures (1–5 atm)

This work aims at clarifying the fundamental mechanisms of non-equilibrium alternating current gliding arc discharge (GAD) by investigating effects of gas compositions and pressures on the GAD characteristics with electrical and optical methods. Interestingly, the glow-to-spark transition was found by adding O2 or CH4 into the argon or modulating the power supply. This transition occurs attributed to the fact that the discharge mode is largely affected by the effective electron decay time (τ) as well as the feedback response of the power supply to the free electron density in the GAD. Short τ or low free electron density tends to result in the spark-type discharge. It further implies that the power supply characteristics is crucial for discharge mode control. The pressure effects on the GAD characteristics were found to vary with gas composition when the same alternating current power supply was used. In N2 or air, the emission intensity from the plasma column increases with pressure while the mean electric field strength (E) along the plasma column decreases with pressure. Differently, in Ar, the emission intensity and E do not change much with pressure. It can be explained by the different energy partition and transfer pathways between monatomic and molecular species. The molecular gases have vibrational excitation pathways to facilitate the electronic excitation and ionization that is different from the monatomic gas.

Understanding the chemical kinetics for plasma in liquid: Reaction mechanism of ethanol reforming in microwave discharge

Toward understanding the chemical nature of fuel reforming in liquid phase discharge, a novel kinetic model with being governed by both mass and energy equations was developed for the first time. The model reliability was verified by experimental results for ethanol reforming with water by microwave discharge plasma in liquid (MDPL). The reaction kinetics of ethanol in MDPL were revealed quantitatively. It illustrated that the key reactive species in the MDPL were H, OH, HCO, C and C x H y radicals, which induced the productions of H 2 , CO and hydrocarbons (CH 4 and C 2 H 2 ). The rate determining steps for ethanol conversion were identified as dehydrogenizing ethanol to C 2 H 5 O firstly, and then splitting to CH 2 O and CH 3 radicals. Those two species of CH 2 O and CH 3 governed the formation of CO and hydrocarbons respectively. In addition, the kinetic control mechanism for ethanol reforming in MDPL determined that ethanol was converted by mixed routes of pyrolysis and steam reforming at low initial ethanol molar concentration in liquid ( C e t h L <50%), and it was converted via only pyrolysis route at C e t h L >50%. Water in the liquid supplied OH radical promoting the conversion of C x H y to CO, thereby it regulated the reaction pathway transition between pyrolysis and steam reforming. The energy transfer pathway for discharge power to chemical energy, very important but never discussed for plasma reforming in liquid, was also simulated. It revealed that a very competitive energy efficiency of ∼85% for ethanol reforming was achieved in the MDPL. • Ethanol reforming was mainly induced by radicals of H, OH, HCO, C and C x H y . • Three reaction pathways for ethanol conversion in plasma were predicted. • Ethanol pyrolysis is the major reaction route for ethanol conversion. • The rate determining step was revealed as ethanol dehydrogenated to C 2 H 5 O. • An excellent energy efficiency of 85% was reached.

Luminescent Lifetime Regulation of Lanthanide-Doped Nanoparticles for Biosensing.

Lanthanide-doped nanoparticles possess numerous advantages including tunable luminescence emission, narrow peak width and excellent optical and thermal stability, especially concerning the long lifetime from microseconds to milliseconds. Differing from other shorter-lifetime fluorescent nanomaterials, the long lifetime of lanthanide-doped nanomaterials is independent with background fluorescence interference and biological tissue depth. This review presents the recent advances in approaches to regulating the lifetime and applications of bioimaging and biodetection. We begin with the introduction of the strategies for regulating the lifetime by modulating the core–shell structure, adjusting the concentration of sensitizer and emitter, changing energy transfer channel, establishing a fluorescence resonance energy transfer pathway and changing temperature. We then summarize the applications of these nanoparticles in biosensing, including ion and molecule detecting, DNA and protease detection, cell labeling, organ imaging and thermal and pH sensing. Finally, the prospects and challenges of the lanthanide lifetime regulation for fundamental research and practical applications are also discussed.

Tribo-Excited Chemical Reaction Using an EuIII Complex with a Stacked Anthracene Framework.

A spin-selective tribo-chemical reaction using a dinuclear lanthanide complex is demonstrated for the first time. The dinuclear complex is composed of two EuIII ions, hexafluoroacetylacetonato ligands, and anthracene-based phosphine oxide bridges. Single-crystal analysis revealed a face-to-face-type anthracene dimer structure in the dinuclear EuIII complex. Mechanical stimulus on the dinuclear EuIII complex induced selective formation of oxidized anthracene. The tribo-chemical reaction is based on a characteristic energy-transfer pathway for the selective formation of an excited triplet state.

A bottom-up perspective on photodynamics and photoprotection in light-harvesting complexes using anti-Brownian trapping.

Single-molecule fluorescence spectroscopy allows direct, real-time observation of dynamic photophysical changes in light harvesting complexes. The Anti-Brownian ELectrokinetic (ABEL) trap is one such single-molecule method with useful advantages. This approach is particularly well-suited to make detailed spectroscopic measurements of pigment-protein complexes in a solution phase because it enables extended-duration single-molecule observation by counteracting Brownian motion. This Perspective summarizes recent contributions by the authors and others that have utilized the unique capabilities of the ABEL trap to advance our understanding of phycobiliproteins and the phycobilisome complex, the primary light-harvesting apparatus of cyanobacteria. Monitoring the rich spectroscopic data from these measurements, which include brightness, fluorescence lifetime, polarization, and emission spectra, among other measurable parameters, has provided direct characterization of pigments and energy transfer pathways in the phycobilisome, spanning scales from single pigments and monomeric phycobiliproteins to higher order oligomers and protein-protein interactions of the phycobilisome complex. Importantly, new photophysical states and photodynamics were observed to modulate the flow of energy through the phycobilisome and suggest a previously unknown complexity in phycobilisome light harvesting and energy transport with a possible link to photoadaptive or photoprotective functions in cyanobacteria. Beyond deepening our collective understanding of natural light-harvesting systems, these and future discoveries may serve as inspiration for engineering improved artificial light-harvesting technologies.

Photoresponsive Covalent Organic Frameworks with Diarylethene Switch for Tunable Singlet Oxygen Generation

Incorporation of molecular switches with light, heat, and electricity responsibility into artificial solids has been developed as a successful strategy to construct stimuli-responsive functional materials. However, precise manipulation of their molecular geometries and electronic structures to control the properties of macroscopic materials still remains a fundamental challenge. Herein, a photoresponsive covalent organic framework (o-COF) with the square lattice was fabricated from the dynamic covalent chemistry reaction of ring-open dithienylethene–dialdehyde with 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (H2TAPP). UV irradiation of the dithienylethene-based units in o-COF afforded its reversible photoisomer (c-COF) in the ring-closed form. In addition to a range of diffraction, microscopic, and gas physical sorption characterizations, spectroscopic investigations with the help of theoretical simulations revealed different photocatalytic activities toward the evolution of singlet oxygen and corresponding photocatalytic oxidation of amines due to the different energy transfer pathways from the porphyrin unit to BBTP photoisomers in these two COFs. Most interestingly, such different photocatalytic behaviors for two COFs could be easily tuned in a reversible manner by adjusting the ring-closed/open form of dithienylethene units by means of UV and visible light.

Biomanipulation impacts on per-and polyfluoroalkyl substances accumulation and trophic transfer in an eutrophic lake.

Manipulation of freshwater food web through species introduction has been used to control the increasing algae in the Wuliangsuhai Lake, which affects not only the pathways of carbon source and energy transfer, but also the transfer of contaminants through food web. Food web relationships between biomanipulation area (BMA) and non-biological manipulation area (NBMA) were investigated using stable carbon (δ13C) and nitrogen (δ15N) isotope analysis. In BMA, the δ13C values in fish species were enriched while δ15N depleted due to the increased inter-species competition. Among the same fish species between BMA and NBMA, lower trophic levels were observed in BMA. Concentrations of target PFASs (ΣPFAS) in fish from BMA were significantly (p<0.05) lower than those from NBMA. Whilst elevated trophic magnification factors (TMFs) of PFASs, especially for perfluoroalkyl carboxylic acids (PFCAs) with long carbon chain length (C9-10), perfluorooctane sulfonate (PFOS), and 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) were exhibited in BMA. We found that biomanipulation through species introduction played an important role in control over lake eutrophication and trophic transfer patterns of PFASs in biota from the altered aquatic ecosystem.

Theoretical study of 8‐hydroxyquinoline derivatives as potential antennas in lanthanide complexes: Photophysical properties and elucidation of energy transfer pathways

AbstractA series of 8‐hydroxyquinoline derivatives were theoretically characterized and tested as potential antennas in a set of designed lanthanide complexes. The molecular structure and ligand localized nature of the excited states were studied in the framework of the multiconfigurational methods CASSCF/NEVPT2 combined with TD‐DFT‐based approaches, which allow applying a fragmentation scheme in the analysis of the most probable sensitization pathway via antenna effect. The photophysical properties of all the complexes and antennas were carefully analyzed, predicting the most probable energy transfer pathways. Rate constants for photophysical processes involved in the mechanism showed a significant contribution of the vibronic coupling in all cases, and the predominant intersystem‐crossing between S1 and T1 states was demonstrated from the analysis of the nature of the wave function of those states. The energy transfer process described herein demonstrates the possibility of Eu(III) and Nd(III) sensitization by the studied ligands. The proposed methodology gives a complete picture of the antenna excited state dynamics.

Rationalized crystal structure augmented highly efficient far-red-emitting double perovskite niobate phosphor for indoor plant growth LED applications

Since the inception of white light-emitting diodes (white LEDs), phosphor-coated LEDs have been in focus owing to the tremendous advantageous that they offer in assorted applications ranging from biomedical to automotive applications, including plant growth. While, plant growth LEDs have been bustling the commercial market, there is ample scope to commercialize the promising far-red (FR) emitting LEDs for potential growth of plants in indoor farming. Herein, a facile and efficient strategy was used to develop Mn4+ (Nb site)- and Sm3+ (La site)- ions-doped Ca2LaNbO6 (CLNO:Mn4+/Sm3+) phosphors with outstanding photoluminescence (PL) properties. The PL properties of CLNO:Mn4+ and CLNO:Sm3+ phosphors showed FR emissions at 650 and 697 nm, respectively. When Mn4+/Sm3+ ions were co-doped in a CLNO host lattice, Rietveld refinement revealed alterations in bond lengths of the CLNO crystal structure, which enhanced the phosphor’s thermal stability and photostability and caused the creation of effective pathways for efficient energy transfer from Sm3+ to Mn4+ ions. Furthermore, the reverse strategy, where the sensitizer (Sm3+) concentration was changed instead of activator (Mn4+) concentration, was used to achieve brilliant FR emission from the CLNO:Mn4+/Sm3+ phosphors and the dominant emission was perceived for the CLNO:0.2Mn4+/1.5Sm3+ phosphor. The internal quantum efficiency of the CLNO:0.2Mn4+/1.5Sm3+ phosphor was increased from 28% (CLNO:0.2Mn4+) to 56%. An LED fabricated by coating a CLNO:Mn4+/Sm3+ phosphor layer on a near-ultraviolet LED chip exhibited excellent FR emission with high color purity and with chromaticity coordinates of (0.733, 0.267). The results obtained for the CLNO:0.2Mn4+/1.5Sm3+ phosphor along with the characteristics of fabricated LED showed the high potential of the phosphor for use in promoting indoor plant growth.

Cyanine-Doped Lanthanide Metal-Organic Frameworks for Near-Infrared II Bioimaging.

Developing metal–organic frameworks (MOFs) with strong near‐infrared II (NIR‐II, 1000–1700 nm) emission is significant for biomedical research but highly challenging. So far there are no MOFs reported for NIR‐II imaging in vivo due to their poor NIR‐II emission efficiency. Herein, a strategy is proposed to prepare MOFs with strong NIR‐II emission, by integrating NIR dye IR‐3C and Ln3+ (Ln = Yb, Nd, and Er) into a same framework. IR‐3C with high photon‐absorption ability harvests the excitation photons and transfers energy to Ln3+ via a resonance energy transfer pathway, significantly enhancing the NIR‐II emission of Ln3+. The as‐obtained Er‐BTC‐IR exhibits excellent NIR‐IIb (1500–1700 nm) emission efficiency in aqueous phase and good biocompatibility after surface modification, which provides advanced bioimaging performance in vivo. It is able to clearly delineate the vessels, spine, and lymph of mice, and also to differentiate the vessels with acute vascular inflammation. This strategy paves the way to the preparation of NIR‐II emissive MOFs and will promote their bioapplication.

Multivalent Supramolecular Assembly Based on a Triphenylamine Derivative for Near-Infrared Lysosome Targeted Imaging.

Near-infrared (NIR) targeted cell imaging has become a research hotspot due to the advantages of deeper tissue penetration, minimal interference from the background signals, and lower light damage. Herein, we report a multivalent supramolecular aggregate with NIR fluorescence emission, which was fabricated from triphenylamine derivatives (TPAs), cucurbit[8]uril (CB[8]), Si-rhodamine (SiR), and hyaluronic acid (HA). Interestingly, possessing a rigid luminescent core and cationic phenylpyridinium units linked by flexible alkyl chains, the tripaddle hexacationic TPA could bind with CB[8] at a 2:3 stoichiometric ratio to form a network-like multivalent assembly with enhanced red luminescence. Such organic two-dimensional network-like aggregate further co-assembled with the energy acceptor SiR and cancer cell targeting agent HA, leading to nanoparticles with NIR emission at 675 nm via an intermolecular energy transfer pathway. Furthermore, the obtained multivalent supramolecular aggregate was successfully applied in lysosome targeted imaging toward A549 cancer cells, which provides a convenient strategy for NIR targeted cell imaging.