We report a cationic porphyrin 5,10,15,20‐tetrakis‐(4‐N‐methylpyridyl)‐porphyrin (TMPyP) that can respond to specific bacteria, followed by adaptable photodynamic/photothermal therapy processes. ...TMPyP could be reduced to phlorin by facultative anaerobes with a strong reducing ability such as E. coli and S. typhimurium in hypoxic environments, possessing strong NIR absorption and remarkable photothermal conversion capacity, thus demonstrating excellent antimicrobial activity (>99 %) by photothermal therapy. While in an aerobic environment with aerobic bacteria, TMPyP functioned as a typical photosensitizer that killed bacteria effectively (>99.9 %) by photodynamic therapy. By forming a host–guest complex with cucurbit7uril, the biocompatibility of TMPyP significantly improved. This kind of bacteria‐responsive porphyrin shows specificity and adaptivity in antimicrobial treatment and holds potential in non‐invasive treatments of bacterial infections.
A cationic porphyrin that can respond to specific bacteria followed by adaptable photodynamic/photothermal therapy is reported. It can be reduced to phlorin by reductive facultative anaerobes in hypoxic environments, possessing NIR photothermal conversion ability and demonstrating excellent antimicrobial activity by photothermal therapy. With aerobic bacteria, it functions as an efficient antibacterial photosensitizer by photodynamic therapy.
The global existence issue in critical spaces for compressible Navier–Stokes equations, was addressed by Danchin (Invent Math 141:579–614,
2000
) and then developed by Charve and Danchin (Arch ...Rational Mech Anal 198:233–271,
2010
), Chen et al. (Commun Pure Appl Math 63:1173–1224,
2010
) and Haspot (Arch Rational Mech Anal 202:427–460,
2011
) in more general
L
p
setting. The main aim of this paper is to exhibit (more precisely) time-decay estimates of solutions constructed in the critical regularity framework. To the best of our knowledge, the low-frequency assumption usually plays a key role in the large-time asymptotics of solutions, which was firstly observed by Matsumura and Nishida (J Math Kyoto Univ 20:67–104,
1980
) in the
L
1
(
R
d
)
space. We now claim
a new low-frequency assumption
for barotropic compressible Navier–Stokes equations, which may be of interest in the mathematical analysis of viscous fluids. Precisely, if the initial density and velocity additionally belong to some Besov space
B
˙
2
,
∞
-
σ
1
(
R
d
)
with the regularity
σ
1
∈
(
1
-
d
/
2
,
2
d
/
p
-
d
/
2
, then a
sharp
time-weighted inequality including enough time-decay information can be available, where
optimal decay exponents for the high frequencies
are exhibited. The proof mainly depends on some non standard Besov product estimates. As a by-product, those optimal time-decay rates of
L
q
–
L
r
type are also captured in the critical framework.
Covalent thermosets generally exhibit robust mechanical properties, while they are fragile and lack the ability to be reprocessed or recycled. Herein, a new strategy of incorporating noncovalent ...bonds into main‐chains is developed to construct tough and multi‐recyclable cross‐linked supramolecular polyureas (CSPU), which are prepared via the copolymerization of diisocyanate monomers, noncovalently bonded diamine monomers linked by quadruple hydrogen bonds, and covalent diamine/triamine monomers. The CSPU exhibit remarkable solvent resistance and outstanding mechanical properties owing to the covalent cross‐linking via triamine monomer. Through the incorporation of 9.7% and 14.6% quadruple hydrogen bonded diamine monomer, the transparent CSPU films are endowed with superior toughness of 74.17 and 124.17 MJ m−3, respectively. Impressively, even after five generations of recycling processes, the mechanical properties of reprocessed CSPU can recover more than 95% of their original properties, displaying excellent multiple recyclablity. As a result, the superior toughness, remarkable solvent resistance, high transparency, and excellent multiple recyclability are well‐combined in the CSPU. It is highly anticipated that this line of research will provide a facile and general method to construct various cross‐linked polymer materials with superior recyclability and mechanical properties.
A new strategy of incorporating noncovalent bonds into main‐chains is developed to construct tough and multi‐recyclable cross‐linked supramolecular polyureas (CSPU). After five generations of recycling processes, the mechanical properties of reprocessed CSPU can recover more than 95% of their original properties. Overall, CSPU exhibit superior toughness, remarkable solvent resistance, high transparency, and excellent multiple recyclability.
Concerning that the residues of photosensitizers (PS) may cause serious side effects under light, it is of great significant to timely switch‐off PS after photodynamic therapy (PDT). Herein, we ...proposed a supramolecular strategy to regulate the activity of PS, fabricating a supramolecular PS with improved reactive oxygen species (ROS) generation efficiency and accelerated self‐degradation ability. During PDT treatment, the supramolecular PS exhibited good therapeutic efficiency as well as reduced dark toxicity. Moreover, the supramolecular PS could be degraded by ROS generated by itself and lose its PDT activities once PDT treatment finished. In this way, the side effects of PDT can be reduced without sacrificing the therapeutic efficiency. This work provides a novel strategy for smarter PDT beacon to further improve the safety of PDT treatment.
A supramolecular photosensitizer with improved ROS generation efficiency and accelerated self‐degradation ability was reported. Apart from the excellent photodynamic therapeutic efficiency and good biocompatibility, the supramolecular photosensitizer could be photodegraded and lose its PDT activity once PDT treatment finished. Therefore, the side effects of PDT can be reduced without sacrificing the therapeutic efficiency.
The development of non‐covalent synthetic strategy to fabricate efficient photocatalysts is of great importance in theranostic and organic materials. Herein, a fluorochrome N,N′‐dimethyl ...2,5‐bis(4‐pyridinium)thiazolo5,4‐dthiazolediiodide (MPT) was transformed into an efficient photocatalyst through supramolecular dimerization in the cavity of cucurbit8uril (CB8). The host‐enhanced charge transfer interaction within the supramolecular dimer 2MPT‐CB8 dramatically promoted intersystem crossing to produce triplet. In addition, the staggered conformation of 2MPT‐CB8 facilitated the energy transfer and electron transfer of the triplet. As a result, 2MPT‐CB8 could serve as a high‐efficiency photocatalyst for the oxidative hydroxylation of arylboronic acids. This supramolecular dimerization strategy enriches the supramolecular engineering of functional π‐systems. It is anticipated that this strategy can be extended to fabricate various π‐systems with tailor‐made functions.
An efficient fluorochrome was transformed into a high‐performance photocatalyst through the facile fabrication of supramolecular dimer. Owing to the host‐enhanced charge transfer interaction, the intersystem crossing was promoted and the followed electron transfer was facilitated. Therefore, the supramolecular dimer exhibited excellent photocatalytic property for the oxidative hydroxylation of arylboronic acids.
Organic radicals are important species with single electrons. Because of their open-shell structure, they are widely used in functional materials, such as spin probes, magnetic materials and ...optoelectronic materials. Owing to the high reactivity of single electrons, they often serve as a key intermediate in organic synthesis. Therefore, tuning the stability of radicals is crucial for their functions. Herein, we summarize covalent and non-covalent approaches to tune the stability of organic radicals through steric effects and tuning the delocalization of spin density. Covalent approaches can tune the stability of radicals effectively and non-covalent approaches benefit from dynamicity and reversibility. It is anticipated that the further development of covalent and non-covalent approaches, as well as the interplay between them, may push the fields forward by enriching new radical materials and radical mediated reactions.
Covalent and non-covalent approaches to tune the stability of organic radicals through steric effects and the delocalization of spin density.
Cucurbit[n]urils for Supramolecular Catalysis Tang, Bohan; Zhao, Jiantao; Xu, Jiang‐Fei ...
Chemistry : a European journal,
December 1, 2020, Letnik:
26, Številka:
67
Journal Article
Recenzirano
The control over chemical reactivity and selectivity are always pursued. Using non‐covalent interactions to achieve efficient and selective catalysis is an essential goal of supramolecular catalysis. ...Supramolecular catalysis based on cucurbitnurils (CBns) possesses distinct characteristics for the unique structure of CBns. CBns are a family of pumpkin‐shaped host molecules with various molecular sizes, rigid structures, electronegative portals and wealthy host‐guest chemistry. Herein, we summarize the three major mechanisms of CBns based supramolecular catalysis. Owing to the structural properties of CBns, CBns can serve as nanoreactors and steric hindrance to modulate the reactivity of substrates. They can also catalyze the reactions by modulating the reactivity of ionized intermediates. Recent progresses on the CBns based supramolecular catalysis are introduced in this Minireview and the future development in this field is discussed. It is anticipated that this review provides insights into the mechanism of CBns based supramolecular catalysis and may help scientists find new opportunities in this field.
The major mechanisms of CBns based supramolecular catalysis are summarized. CBns can serve as nanoreactors and steric hindrance to modulate the reactivity of substrates. They can also catalyze the reactions by modulating the reactivity of ionized intermediates. Recent progresses on the CBns‐based supramolecular catalysis are also introduced. It is anticipated that this review helps scientists find new opportunities in this field.
A supramolecular complex that can be selectively reduced to radical anions in situ by facultative anaerobic bacteria is reported. To this end, a water‐soluble bifunctional monomer bearing perylene ...diimide was synthesized, and its supramolecular complex with cucurbit7uril was fabricated on the basis of host–guest complexation, which could be reduced to forming radical anions in the presence of E. coli. It was found that this supramolecular complex could display different ability of generating radical anions by facultative anaerobic and aerobic bacteria in terms of their various reductive abilities. The selective antibacterial activity of the supramolecular complex could be realized by the photothermal performance of the radical anions under near‐infrared irradiation. It is anticipated that this method may lead to a novel bacteria‐responsive photothermal therapy to regulate balance of bacterial flora.
Photothermal therapy: A supramolecular complex of a perylene diimide derivative and cucurbit7uril shows different possibilities of generating radical anions by facultative anaerobic and aerobic bacteria. The selective antibacterial activity of the supramolecular complex is based on the photothermal effect of the radical anions that convert optical energy into heat under near‐infrared illumination.
Photothermal therapy at the NIR‐II biowindow (1000–1350 nm) is drawing increasing interest because of its large penetration depth and maximum permissible exposure. Now, the supramolecular radical ...dimer, fabricated by N,N′‐dimethylated dipyridinium thiazolo5,4‐dthiazole radical cation (MPT.+) and cucurbit8uril (CB8), achieves strong absorption at NIR‐II biowindow. The supramolecular radical dimer (2MPT.+‐CB8) showed highly efficient photothermal conversion and improved stability, thus contributing to the strong inhibition on HegG2 cancer cell under 1064 nm irradiation even penetrating through chicken breast tissue. This work provides a novel approach to construct NIR‐II chromophore by tailor‐made assembly of organic radicals. It is anticipated that this study provides a new strategy to achieve NIR‐II photothermal therapy and holds promises in luminescence materials, optoelectronic materials, and also biosensing.
Host‐enhanced intermolecular charge transfer enabled the fabrication of a supramolecular radical dimer with strong absorption in the NIR‐II biowindow and high stability. The dimer exhibited high‐efficiency photothermal conversion and strong inhibition on cancer cells through NIR‐II photothermal therapy.
This study applies a network approach to develop a model that highlights the role of resource acquisition through networks as an important mediating mechanism through which entrepreneurial ...orientation influences firm performance. This approach provides an alternative explanation for the divergent findings of the EO-performance relationship. We also investigate how business and political ties, differently and configurationally, shape the relationship between EO and network resource acquisition. Empirical findings from a study of 251 firms provide general support for the hypotheses, highlighting the unique value of leveraging a network approach to reconsider the performance-enhancing mechanism of entrepreneurial orientation.
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