H-and J-aggregation of conjugated small molecules in organic solar cells

As H-and J-aggregation receive more and more attention in the research of organic solar cells(OSCs),especially in small molecular systems,deep understanding of aggregation behavior is needed to guide the design of conjugated small molecular structure and the fabrication process of OSC device.For this end,this review is written.Here,the review firstly introduced the basic information about H-and J-aggregation of conjugated small molecules in OSCs.Then,the characteristics of H-and J-aggregation and the methods to identify them were summarized.Next,it reviewed the research progress of H-and J-aggregation of conjugated small molecules in OSCs,including the factors influencing H-and J-aggregation in thin film and the effects of H-and J-aggregation on OPV performance.

Metal ions-bridged J-aggregation mediated nanoassembly composition for breast cancer phototherapy

Recently, the highly ordered J-aggregates of organic dyes with intriguing optical properties have received considerable attention in biomedical applications. Herein, binary metal ions Mn(Ⅱ)/Fe(Ⅲ) are used to induce the formation of indocyanine green(ICG) J-aggregates.Further, the sheet-like J-aggregates are able to act as "carriers" for loading hydrophobic chemotherapeutic gambogic acid(GA), realizing the effect of "killing two birds with one stone" for both treatment and delivery. The as-designed nanoassembly is formed spontaneously in aqueous environment via π-π stacking, electrostatic interaction, and hydrophobic force, exhibiting enhanced photostability of ICG and outstanding reactive oxygen species(ROS) generation ability. Moreover, significant inhibition of tumor growth by the synergetic effect of phototherapy and chemotherapy is verified in a subcutaneous4T1 tumors model. In conclusion, this work not only presents a facile and green approach to manufacture carrier-free nanodrugs, but also establishes a universal platform that has potential application in the co-delivery of near-infrared dye and hydrophobic molecules.

J-aggregation of photosensitizers leads to an ultrahigh drug-loading system for targeted delivery

Drug loading capacity is very important in the construction of targeted drug delivery systems(TDDSs)for the improvement of drug delivery efficiency.However,the drug-loading capacity of most nanomaterials is non-idealistic,and developing the high drug-loading TDDSs is still a critical challenge.In this work,an ultrahigh loading system(denoted as HMPB_(2))was prepared via J-aggregation of an aza-boron dipyrromethene derivative(Bod)by using hollow MnO_(2)modified with glucosamine pillar[5]arene as a carrier,which was demonstrated to have typical J-aggregate absorption of Bod,specific cancer cells targeting ability,negligible dark cytotoxicity,and potent phototoxicity.This work provides a successful example to construct an ultrahigh drug-loading system via J-aggregation for targeted delivery.

Induced J-aggregation in acceptor alloy enhances photocurrent

Carbon-oxygen-bridged (CO-bridged) ladder-type units already proved to be promising electron-donating building blocks for making acceptor-donor-acceptor (A-D-A) nonfullerene acceptors [1].Compared with traditional carbon-bridged (C-bridged) units, CObridged units present stronger electron-donating capability due to electron-rich oxygen atoms.

Infrared Spectroscopic Investigations of J-aggregates of Protonated Tetraphenylporphine

Protonated tetraphenylporphine（H2TPP） J-aggregates were prepared by aggregation on the liquid-air interface. Using FTIR spectroscopy, the authors observed the infrared absorption spectra of H2TPP and its J-aggregates. The IR spectra of H2TPP J-aggregates show significant changes compared with that of HETPP monomer. Intensity changes（e.g., strong enhancement of the in-plane vibronic mode and weakening of the out-of-plane vibronic mode of phenyl and porphyrin skeletal） were interpreted on the basis of stacking effects. Observation of the same type of bands collapse into single band was explained by the increase in the symmetry of H2TPP molecules. And the new bands at 1635 and 3407 cm^-1 indicate the aggregates containing a large amount of bound water.

Templated J-Aggregate Nanotubes for the Detection of Dopamine

J-aggregates of dye molecules are a unique supramolecular structure, which shows great promise in photoelectric devices due to its remarkable optical and transport properties. In this paper, we report the templated formation of J-aggregate nanotubes by the adsorption of 3,3’-diethylthiacarbocyanine iodide on the self-assembled nanotubes of lithocholic acid. The optical and electronic properties of the templated J-aggregate nanotubes are studied. A sensor platform is fabricated by depositing the J-aggregate nanotubes on interdigitated gold electrodes for the detection of dopamine (DA). We find that the current change of the J-aggregate nanotube-based sensor platform in response to DA is linear in the concentration range from 10 nM to 70 nM, giving the detection limit of 0.27 nM.

Langmuir-Blodgett Films from Schiff Base Aluminium (Ⅲ) Complex

The characteristics of the LB films of Schiff base aluminium(Ⅲ), tris(2-hydroxy-5-nitro-N-dodecyl-benzylideneaminato) aluminium(Ⅲ)[Al(TA12)_3], were studied. The surface pressure-area(π-A) isotherm of Al(TA12)_3 in the pure water subphase was investigated. The molecular area, 0.48 nm^2, is one-third of the expected value that indicates the formation of an aggregate. The Langmuir-Blodgett(LB) films of Al(TA12)_3 were transferred and characterized. The UV-Vis spectra and the AFM image both confirmed that the J-aggregates formed. The polarized UV-Vis spectra indicated that the complex plane had to be oriented with an angle of about 30° to the substrate surface. The IR spectra suggested that the complexation took place between aluminium ions and the oxygen atoms of the ligand rather than the nitrogen atom.

AFM Height Measurements of Molecular Layers of a Carbocyanine Dye

Atomic force microscopy (AFM) was used for the morphological characterization and precise height meas-urements of two-dimensional molecular layers of carbocyanine dye 3,3’-di(r-sulfopropyl)-4,4’,5,5’-dibenzo-9-ethylthiacarbocyanine betaine pyridinium salt. The AFM measurements reveal three morphological types of molecular aggregates: leaves, stripes and spots. The leaves are stripes have same monolayer height ~1.4 nm and different crystal shapes: the leaves are monoloyers with the lens shape and the stripes are bilay-ers with the shape of extended rectangles. The monolayer height ~1.4 nm was interpreted as indicating the symmetrical packing arrangement of dye molecules. In the symmetrical monolayer, the sulfopropyl groups of all-trans monomer units are located on both monolayer sides whereas the adjacent stacked dye molecules have a lateral slippage providing the J-aggregate optical properties. The lower height of spots ~1 nm was explained by the model of an asymmetric monolayer with sulfopropyl groups of all-trans monomers occupy-ing the same position with respect to the monolayer plane. The packing arrangement of all-trans monomers in the asymmetric monolayer corresponds to H-aggregate. The alternative models of the packing arrange-ment in monolayers with mono-cis1 monomer configuration are discussed.

Engineering J-aggregates for NIR-induced meso-CF_(3)-BODIPY nanoparticles by activated apoptosis mechanism in photothermal therapy

Forming J-aggregates by organic monomer is a fascinating strategy to urge spectroscopic redshift with respect to that of the monomer.Herein,we designed 1,7-diphenyl-substituted meso–CF_(3)-BDP monomer confirmed by X-ray crystallographic analysis.The low-barrier rotation of the–CF_(3)group in meso–CF_(3)-BDP1 significantly enhances the non-radiative efficiency,and the photothermal conversion efficiency(PCE)of the self-assembled nanoparticles(1-NPs:λ_(abs)=746 nm)by J-aggregates was 82%.1-NPs could effectively block cell cycle progression,inhibit cancer cell proliferation and trigger cell apoptosis under low power laser irradiation(0.2 W/cm^(2)).This study proposes an alternate molecular design platform by J-aggregates to promote PCE through the insertion of rotating segment and trigger the cancer cells apoptosis in photothermal therapy at low power laser density.

The unexpected“butterfly effect”of Pt-coordinated cyanine self-assembly for enhanced tumor photothermal therapy

J-aggregates of cyanine have shown great merits in tumor photothermal therapy(PTT)due to their distinct redshift absorption as well as superior photothermal conversion efficiency(PCE).However,due to the complexity of intermolecular interactions,especially the impact of steric hindrance on aggregation,exploring effective strategies to regulate the aggregation modes of organic materials remains challenging.Herein,steric hindrance-regulated J-aggregation of near-infrared(NIR)cyanine was reported based on Pt-coordinated cyanine self-assembly with unexpected“butterfly effect”.Two Pt-coordinated cyanine dimers CyR-Pt(R=Me and Et)were synthesized and spontaneously self-assembled into aggregates in aqueous solution.CyEt-Pt aggregates were loose and amorphous stacking.By replacing ethyl with methyl to reduce steric hindrance,a tiny change resulted in the generation of tightly stacked cyanine J-aggregates(thickness less than 3 nm)observed in CyMe-Pt self-assembly.Significantly,this unexpected“butterfly effect”enabled CyMe-Pt J-aggregates to effectively inhibit reactive oxygen species and greatly improve its photostability.Besides,CyMe-Pt J-aggregates with NIR-II absorption exhibited outstanding photothermal stability and higher PCE(η=37%)than CyEt-Pt disordered aggregates(η=20%).Evident tumor suppression performance of CyMe-Pt J-aggregates was validated under 980 nm laser irradiation,demonstrating its great potential in tumor PTT.

Exciton polaritons based on planar dielectric Si asymmetric nanogratings coupled with J-aggregated dyes film

Optical cavity polaritons,originated from strong coupling between the excitons in materials and photons in the confined cavities field,have recently emerged as their applications in the high-speed lowpower polaritons devices,low-threshold lasing and so on.However,the traditional exciton polaritons based on metal plasmonic structures or Fabry-Perot cavities suffer from the disadvantages of large intrinsic losses or hard to integrate and nanofabricate.This greatly limits the applications of exciton poalritons.Thus,here we implement a compact low-loss dielectric photonic–organic nanostructure by placing a 2-nm-thick PVA doped with TDBC film on top of a planar Si asymmetric nanogratings to reveal the exciton polaritons modes.We find a distinct anti-crossing dispersion behavior appears with a 117.16 meV Rabi splitting when varying the period of Si nanogratings.Polaritons dispersion and mode anti-crossing behaviors are also observed when considering the independence of the height of Si,width of Si nanowire B,and distance between the two Si nanowires in one period.This work offers an opportunity to realize low-loss novel polaritons applications.

EFFECTS OF J-AGGREGATES OF IONIC CYANINES ON THE J-AGGREGATES OF IONIC CYANINES WITH OPPOSITE CHARGES

Recently we have reported our study on the J-aggregate formation of an anionic cyanine promoted by the counterions of added salts under environmental conditions. The result showed that the counterions are bound to the dye ion J-stacks in 'stoichiometric' relation. Concerning the fact that polyeletrolytes could promote the formation of J-aggregate of cyanine dye ions, the authors suggested that the J-aggregates of an ionic cyanine might more easily induce the J-aggregation of other cyanine ions with opposite charges. The two

One-Pot Preparation of Highly Dispersed Second Near-Infrared J-Aggregate Nanoparticles Based on FD-1080 Cyanine Dye for Bioimaging and Biosensing

Bioimaging and biosensing in the second nearinfrared(NIR-II)window have attracted great attention due to their unprecedented high temporal–spatial resolution,sensitivity,and penetration depth.Although some organic fluorescence dyes have been developed in this window,it is still a great challenge to synthesize hydrophilic organic contrast agents with both absorbance and emission wavelengths beyond 1300 nm.J-aggregation is a facile pathway to achieve the wavelength red-shift of organic dyes to the NIR-II window and simultaneously improve their hydrophilicity.Here,we report FD-1080 J-aggregates(FD-J)with absorbance of 1360 nm and emission of 1370 nm through heating H-aggregated FD-1080 cyanine dyes in an aqueous solution.With FD-J administration,real-time imaging of mice brain and hindlimb vasculatures can be performed beyond 1500 nm.Meanwhile,arterial and venous vessels can be clearly distinguished through dynamic imaging after injection of FD-J.In addition,reactive oxygen species-responsive NIR-II ratiometric fluorescence sensors were available based on FD-J and lanthanide nanoparticles to enable the detection of inflammation in living mice.

Aggregation behavior of amphiphilic D-π-A molecules bearing recognition group

Aggregation behavior of two amphiphilic D-π-A molecules bearing barbituric acid as both recogniton group and electron-drawing substituent , 5-(4-dodecyl oxybenzylidene)-(1H, 3H)-2,4,6-pyrimidine trione (PB12) and 5-(4-N,N-didodecyl aminobenzylidene)-(1H,3H)-2,4,6-pyrimidine trione (AB12) was studied by UV-visible, fluorescence, and surface voltaic spectroscopies (SPS). The experimental results indicate that PB12 tends to form J-aggregate and AB12 tends to form H-aggregate under increasing concentration. An intramolecular twisted charge transfer (TICT) emission around 500 nm is observed when J-aggregate is formed between PB12 molecules, and an excimer emission around 600 nm is observed when H-aggregate is formed between AB12 molecules.

Porous Pyrene Organic Cage with Unusual Absorption Bathochromic-Shift Enables Visible Light Photocatalysis

We have constructed a novel porous pyrene-based organic cage,PyTC1,through the condensation reaction of cyclohexanediamine with 5,5′-(pyrene-1,6-diyl)diisophthalaldehyde.Single-crystal X-ray diffraction analysis reveals the effective intercage C–H...πinteraction between cyclohexanediimine and pyrene segments.Such a soft intercage C–H...πinteraction,rather than a classic J-aggregate with slippedπ–π-stacking configuration,induced an unusual bathochromic shift of pyrene-based chromophore absorption from an ultraviolet region of PyTC1 in solution to the visible light region of PyTC1 in solid-state.

Micellization of copolymers via noncovalent interaction with TPPS and aggregation of TPPS

Aggregation of 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) was investigated in complex micelles composed of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP) and poly(2-(dimethylamino)ethyl methylacrylate)-b-poly(Nisopropylacrylamide) (PDMAEMA-b-PNIPAM) in aqueous solutions.The resultant complex micelles had a complex P4VP/ PDMAEMA/TPPS core and a mixed PEG/PNIPAM shell.Different noncovalent interaction modes between the porphyrin and each copolymer accomplished a co-effect on the aggregation of TPPS.The formation of aggregates was pH-dependent.At pH 3.2–6.5,TPPS existed as a mixture of H-aggregates and monomers because of the aromatic-aromatic interaction with P4VP and electrostatic interaction with PDMAEMA.The monomers translated into J-aggregates,stabilized by electrostatic interaction with the both polyelectrolyte blocks,upon decreasing the pH to 1.6.The free-base monomer was the one and only form for the dye at pH 11.0 due to aromatic stacking with the pyridyl rings.