Heterocyclic polymers have gained enormous attention for their unique functionalities and wide applications. In contrast with the well-studied polymer systems with five- or six-membered heterocycles, ...functional polymers with readily openable small-ring heterocycles have rarely been explored due to their large synthetic difficulty. Herein, a facile one-pot multicomponent polymerization to such polymers is developed. A series of functional polymers with multisubstituted and heteroatom-rich azetidine frameworks are efficiently generated at room temperature in high atom economy from handy monomers. The four-membered azetidine rings in the polymer skeletons can be easily transformed into amide and amidine moieties via a fast and efficient acid-mediated ring-opening reaction, producing brand-new polymeric materials with distinctive properties. All the as-prepared azetidine-containing polymers exhibit intrinsic visible luminescence in the solid state under long-wavelength UV irradiation even without conventionally conjugated structures. Such unconventional luminescence is attributed to the clusteroluminogens formed by through-space electronic interactions of heteroatoms and phenyl rings. All the obtained polymers show excellent optical transparency, high and tunable refractive indices, low optical dispersions and good photopatternability, which make them promising materials in various advanced electronic and optoelectronic devices. The ring-opened polymers can also function as a lysosome-specific fluorescent probe in biological imaging.
Peroxynitrite (ONOO
−
) is a powerful and short-lived oxidant formed
in vivo
, which can react with most biomolecules directly. To fully understand the roles of ONOO
−
in cell biology, improved ...methods for the selective detection and real-time analysis of ONOO
−
are needed. We present a water-soluble, luminescent europium(
iii
) probe for the rapid and sensitive detection of peroxynitrite in human serum, living cells and biological matrices. We have utilised the long luminescence lifetime of the probe to measure ONOO
−
in a time-resolved manner, effectively avoiding the influence of autofluorescence in biological samples. To demonstrate the utility of the Eu(
iii
) probe, we monitored the production of ONOO
−
in different cell lines, following treatment with a cold atmospheric plasma device commonly used in the clinic for skin wound treatment.
Reactivity-based europium(
iii
) probe displays excellent selectivity for peroxynitrite (ONOO
−
), enabling its time-resolved luminescence detection in living cells.
The development of synthetic receptors for the selective binding and discrimination of anions in water requires an understanding of how anions interact with these synthetic receptors. Molecules ...designed to differentiate nucleoside phosphate anions (
e.g.
ATP, ADP, GTP, GDP, UDP) under physiological conditions could underpin exciting new sensing tools for biomedical research and drug discovery, but it is very challenging due to the similarities in anion structure, size and charge. We present a series of lanthanide-based anion receptors and establish key structural elements that impact on nucleoside phosphate anion binding and sensing. Structural evidence of anion binding using X-ray crystallographic and NMR data, supported by DFT calculations indicate the binding modes between the lanthanide complexes and certain phosphoanions, revealing a bidentate (α-, γ-) binding mode to ATP. We further use four of the receptors to allow discrimination of eight nucleoside phosphate anions in the first array-based assay using lanthanide complexes, taking advantage of the multiple emission bands and long emission lifetimes associated with luminescent lanthanide complexes.
Discrimination of nucleoside phosphate anions in the first supramolecular sensing array using luminescent lanthanide complexes.
Lipid droplets are highly associated with obesity, diabetes, inflammatory disorders, and cancer. A reliable two-photon dye for specific lipid droplets imaging in live cells and live tissues at ...ultralow concentration has rarely been reported. In this work, four new aggregation-induced emission luminogens (AIEgens) based on the naphthalene core were designed and synthesized for specific two-photon lipid droplet staining. The new molecules, namely, NAP AIEgens, exhibit large Stokes shift (>110 nm), high solid-state fluorescence quantum yield (up to 30%), good two-photon absorption cross section (45–100 GM at 860 nm), high biocompatibility, and good photostability. They could specifically stain lipid droplets at ultralow concentration (50 nM) in a short time of 15 min. Such ultralow concentration is the lowest value for lipid droplets staining in live cells reported so far. In vitro and ex vivo two-photon imaging of lipid droplets in live cells and live mice liver tissues were successfully demonstrated. In addition, selective visualization of lipid droplets in live mice liver tissues could be achieved at a depth of about 70 μm. These excellent properties render them as promising candidates for investigating lipid droplet-associated physiological and pathological processes in live biological samples.
The known dichloride complexes TiCl
2
L(O)
2
(OR)
2
(type I: R = Me (
1
),
n
-Pr (
2
) and
n
-pentyl (
3
); L(OH)
2
(OR)
2
= 1,3-dialkyloxy-
p-tert
-butylcalix4arene), together with the new ...complexes {TiL(O)
3
(OR)
2
(μ-Cl)
2
}·6MeCN (R =
n
-decyl (
4
·6MeCN)), and Ti(NCMe)Cl(L(O)
3
(OR))·MeCN (type II: R = Me,
5
·MeCN) are reported. Attempts to prepare type II for R =
n
-Pr and
n
-pentyl using TiCl
4
resulted in the complexes {TiL(O)
3
(O
n
-propyl)
2
(μ-Cl)(μ-OH)}
6
·7MeCN and {TiL(O)
3
(O
n
-pentyl)
2
(μ-Cl)(μ-OH)}·7.5MeCN (
7
·7.5MeCN), respectively; use of TiCl
4
(THF)
2
resulted in a co-crystallized THF ring-opened product Ti(NCMe)(μ
3
-O)L(O)
4
TiCl(O(CH
2
)
4
Cl)
2
-2TiCl(NCMe)(L(O)
3
(O
n
-Pr))·11MeCN (
8
·11MeCN). The molecular structures of
2
·2MeCN,
4
·6MeCN, and
5
·MeCN together with the hydrolysis products {TiL(O)
3
(OR)
2
(μ-Cl)(μ-OH)} (R =
n
-Pr
6
·7MeCN;
n
-pentyl,
7
·7.5MeCN,
9
·9MeCN); R =
n
-decyl
10
·8.5MeCN) and that of the ring opened product
8
·11MeCN and the co-crystallized species Ti
2
(OH)Cl(L(O)
3
(OR))L(OH)
2
(OR)
2
·2.85(C
2
H
3
N)·0.43(H
2
O) (R =
n
-pentyl,
11
·2.85(C
2
H
3
N)·0.43(H
2
O)) are reported. Type I and II complexes have been screened for their ability to act as catalysts in the ring opening polymerization (ROP) of -caprolactone ( -CL), δ-valerolactone (δ-VL), ω-pentadecalactone (ω-PDL) and
rac
-lactide (
r
-LA), both with and without benzyl alcohol present and either under N
2
or in air. The copolymerization of -CL with δ-VL and with
r
-LA has also been investigated. For the ROP of -CL, all performed efficiently (>99% conversion) at 130 °C over 24 h both under N
2
and in air, whilst over 1 h, for the type I complexes the trend was
3
>
2
>
1
but all were poor (≤12% conversion). By contrast,
5
over 1 h at 130 °C was highly active (85% conversion). At 80 °C, the activity trend followed the order
5
4
>
3
>
2
>
1
. For δ-VL, at 80 °C the activity trend
5
4
>
1
>
2
>
3
was observed. ROP of the larger ω-PDL was only possible using
5
at 130 °C over 24 h with moderate activity (48% conversion). For
r
-LA, only low molecular weight products were obtained, whilst for the co-polymerization of -CL with δ-VL using
5
, high activity was observed at 80 °C affording a polymer of molecular weight >23 000 Da and with equal incorporation of each monomer. In the case of -CL/
r
-LA co-polymerization using
5
either under N
2
or air, the polymerization was more sluggish and only 65% conversion of CL was observed and the resultant co-polymer had 65 : 35 incorporation. Complex
5
could also be supported on silica, however this system was not as active as its homogeneous counterpart. Finally, the activity of these complexes is compared with that of three benchmark species: a di-phenolate Ti compound {TiCl
2
(2,2′-CH
3
CH4,6-(
t
-Bu)
2
C
6
H
2
O
2
)} (
12
) and a previously reported NO
2
-containing titanocalix4arene catalyst, namely cone-5,17-bis-
tert
-butyl-11,23-dinitro-25,27-dipropyloxy-26,28-dioxo-calix4arene titanium dichloride (
13
), as well as Ti(O
i
-Pr)
4
; the parent calixarenes were also screened.
Titanocalix4arenes are shown to be active for the ROP of cyclic esters under N
2
or air with the mono-methoxy complex Ti(NCMe)Cl(
p-tert
-butylcalix4arene(O)
3
(OMe)) performing best.
Interaction of p‐tert‐butylcalix8areneH8 (L8H8) with NaVO(OtBu)4 (formed in situ from VOCl3) afforded the complex Na(NCMe)5(VO)2L8H⋅4 MeCN (1⋅4 MeCN). Increasing NaVO(OtBu)4 to 4 equiv led to ...Na(NCMe)62(Na(VO)4L8)(Na(NCMe))32⋅10 MeCN (2⋅10 MeCN). With adventitious oxygen, reaction of 4 equiv of VO(OtBu)3 with L8H8 afforded the alkali‐metal‐free complex (VO)4L8(μ3‐O)2 (3); solvates 3⋅3 MeCN and 3⋅3 CH2Cl2 were isolated. For the lithium analogue, the order of addition had to be reversed such that lithium tert‐butoxide was added to L8H8 and then treated with 2 equiv of VOCl3; crystallisation afforded (VO2)2Li6L8(thf)2(OtBu)2(Et2O)2⋅Et2O (4⋅Et2O). Upon extraction into acetonitrile, Li(NCMe)4(VO)2L8H⋅8 MeCN (5⋅8 MeCN) was formed. Use of the imido precursors V(NtBu)(OtBu)3 and V(Np‐tolyl)(OtBu)3 and L8H8, afforded tBuNH3{V(p‐tolylN)}2L8H⋅3 1/2 MeCN (6⋅3 1/2 MeCN). The molecular structures of 1 to 6 are reported. Complexes 1, 3, and 4 were screened as precatalysts for the polymerisation of ethylene in the presence of cocatalysts at various temperatures and for the copolymerisation of ethylene with propylene. Activities as high as 136 000 g (mmol(V) h)−1 were sometimes achieved; higher molecular weight polymers could be obtained versus the benchmark VO(OEt)Cl2. For copolymerisation, incorporation of propylene was 7.1–10.9 mol % (compare 10 mol % for VO(OEt)Cl2), although catalytic activities were lower than VO(OEt)Cl2.
Copolymerisation catalyst: Interaction of p‐tert‐butylcalix8areneH8 with MOtBu and VOCl3 (M=Li, Na, K) affords vanadium(V) oxo calix8arene complexes. Imido complexes were also formed with V(NR)(OtBu)3 (R=tBu, p‐tolyl). Molecular structures are presented, along with activities as precatalysts for the polymerisation of ethylene and copolymerisation with propylene (see picture). Higher molecular weight polymers could be obtained versus the benchmark VO(OEt)Cl2 and incorporation of propylene was 7.1–10.9 mol % (10 mol % for VO(OEt)Cl2), although catalytic activities were lower.
Reactions of différent combinations of group V alkoxides or tungsten oxyalkoxide salts with
p-tert
-butylcalix8areneH
8
(L
8
H
8
) affords mixed-metal calix8arene systems. Intruiging molecular ...structures are formed and the systems are capable of the ring opening polymerisation of -caprolactone under N
2
, air, or as melts affording mostly low molecular weight products.
Combinations of group V alkoxides or tungsten oxyalkoxide salts with
p-tert
-butylcalix8areneH
8
afford mixed-metal calixarenes capable of the ROP of -caprolactone.
A variety of lithiated calixnarenes, for which n = 6 or 8, have been isolated, structurally characterized, and evaluated as catalysts for the ring-opening polymerization (ROP) of the cyclic esters ...ε-caprolactone (ε-CL), δ-valerolactone (δ-VL), and rac-lactide (r-LA). In particular, interaction of p-tert-butylcalix6areneH6 (L6H6) with LiOtBu in THF led to the isolation of Li14(L6H)2(CO3)2(THF)6(OH2)6·14THF (1·14THF), the core of which has a chain of five Li2O2 diamonds. Similar use of p-tert-butylcalix8areneH8 (L8H8) afforded Li10(L8)(OH)2(THF)8·7THF (2·7THF), where the core is composed of a six-rung Li–O ladder. Use of debutylated calix8areneH8 (deBuL8H8) led to an elongated dimer Li18(deBuL8)2(OtBu)2(THF)14·4THF (3·4THF) in which the calix8arenes possess a wavelike conformation forming bridges to link three separate Li x O y clusters (where x and y = 6, ignoring the THF donor oxygens). Interaction of L8H8 with LiOH·H2O afforded Li4(L8H4)(OH2)4(THF)6·5.5THF (4·5.5THF), where intramolecular H-bond interactions involving Li, O, and H construct a cage in the core of the structure with six- and eight-membered rings. Lastly, addition of Me3Al to the solution generated from L8H8 and LiOtBu led to the isolation of (AlMe2)2Li20(L8H2)2(OH2)4(O2–)4(OH)2(NCMe)12·10MeCN (5·10MeCN) in which Li, O, Al, and N centers build a polyhedral core. These complexes have been screened for their potential to act as precatalysts in the ring-opening polymerization (ROP) of ε-CL, δ-VL, and r-LA. For the ROP of ε-CL, δ-VL, and r-LA, systems 1–4 exhibited moderate activity at 130 °C over 8 h. In the case of ROP using the mixed-metal (Li/Al) system 5, better conversions and high molecular weight polymers were achieved. In the case of the ROP of ω-pentadecalactone (ω-PDL), the systems proved to be inactive under the conditions employed herein.
We have structurally characterized a number of lithiated calix4arenes, where the bridge in the calix4arene is thia (-S-, L
S
H
4
), sulfinyl (-SO-, L
SO
H
4
), sulfonyl (-SO
2
-, L
SO2
H
4
), ...dimethyleneoxa (-CH
2
OCH
2
-, L
COC
H
4
) or methylene (-CH
2
-, LH
4
). In the case of L
4S
H
4
, interaction with LiO
t
Bu led to the isolation of the complex Li
8
(L
4S
)
2
(THF)
4
·5THF (
1
·5THF), whilst similar interaction of L
4SO
H
4
led to the isolation of Li
6
(L
4SO
H)
2
(THF)
2
·5(THF) (
2
·5THF). Interestingly, the mixed sulfinyl/sulfonyl complexes Li
8
(calix4arene(SO)(SO
2
)(SO
1.68
)
2
)
2
(THF)
6
·8(THF) (
3
·8THF) and Li
5
Na(L
SO/3SO2
H)
2
(THF)
5
·7.5(THF) (
4
·7.5(THF) have also been characterized. Interaction of LiO
t
Bu with L
SO2
H
4
and L
COC
H
4
afforded Li
5
L
4SO2
(OH)(THF)
4
·2THF (
5
·2THF) and Li
6
(L
COC
)
2
(HO
t
Bu)
2
·0.78THF·1.22hexane (
6
·0.78THF·1.22hexane), respectively. In the case of LH
4
, reaction with LiO
t
Bu in THF afforded a monoclinic polymorph LH
2
Li
2
(thf)(OH
2
)
2
·3THF (
7
·3THF) of a known triclinic form of the complex, whilst reaction of the de-butylated analogue of LH
4
, namely de-BuLH
4
, afforded a polymeric chain structure {Li
5
(de-BuL)(OH)(NCMe)
3
·2MeCN}
n
(
8
·2MeCN). For comparative catalytic studies, the complex Li
6
(L
Pr
)
2
(H
2
O)
2
·hexane (
9
hexane), where L
Pr2
H
2
= 1,3-di-
n
-propyloxycalix4areneH
2
, was also prepared. The molecular crystal structures of
1-9
are reported, and their ability to act as catalysts for the ring opening (co-)/polymerization (ROP) of the cyclic esters -caprolactone, δ-valerolactone, and
rac
-lactide has been investigated. In most of the cases, complex
6
outperformed the other systems, allowing for higher conversions and/or greated polymer
M
n
.
Novel Li-calix
n
arene complexes (
n
= 3, 4) having (-S-), (-SO-), (-SO
2
-), (-CH
2
OCH
2
-) or (-CH
2
-) bridges have been synthesized and fully characterized. Their catalytic activity in the ring opening polymerization of lactones has been studied.
From reactions involving sodium molybdate and dianilines 2,2′-(NH2)C6H42(CH2)n (n = 0, 1, 2) and amino-functionalized carboxylic acids 1,2-(NH2)(CO2H)C6H4 or 2-H2NC6H3-1,4-(CO2H)2, in the presence of ...Et3N and Me3SiCl, products adopting H-bonded networks have been characterized. In particular, the reaction of 2,2′-diaminobiphenyl, 2,2′-NH2(C6H4)2, and 2-aminoterephthalic acid, H2NC6H3-1,4-(CO2H)2, led to the isolation of (MoCl32,2′-N(C6H4)2}{HNC6H3-1-(CO2),4-(CO2H)·22,2′-NH2(C6H4)2·3.5MeCN (1·3.5MeCN), which contains intra-molecular N–H∙∙∙Cl H-bonds and slipped π∙∙∙π interactions. Similar use of 2,2′-methylenedianiline, 2,2′-(NH2)C6H42CH2, in combination with 2-aminoterephthalic acid led to the isolation of MoCl2(O2CC6H3NHCO2SiMe3)(NC6H4CH2C6H4NH2)·3MeCN (2·3MeCN). Complex 2 contains extensive H-bonds between pairs of centrosymmetrically-related molecules. In the case of 2,2′ethylenedianiline, 2,2′-(NH2)C6H42CH2CH2, and anthranilic acid, 1,2-(NH2)(CO2H)C6H4, reaction with Na2MoO4 in the presence of Et3N and Me3SiCl in refluxing 1,2-dimethoxyethane afforded the complex MoCl3{1,2-(NH)(CO2)C6H4}{NC6H4CH2CH2C6H4NH3}·MeCN (3·MeCN). In 3, there are intra-molecular bifurcated H-bonds between NH3 H atoms and chlorides, whilst pairs of molecules H-bond further via the NH3 groups to the non-coordinated carboxylate oxygen, resulting in H-bonded chains. Complexes 1 to 3 have been screened for the ring opening polymerization (ROP) of both ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) using solvent-free conditions under N2 and air. The products were of moderate to high molecular weight, with wide Ð values, and comprised several types of polymer families, including OH-terminated, OBn-terminated (for PCL only), and cyclic polymers. The results of metal-free ROP using the dianilines 2,2′-(NH2)C6H42(CH2)n (n = 0, 1, 2) and the amino-functionalized carboxylic acids 1,2-(NH2)(CO2H)C6H4 or 2-H2NC6H3-1,4-(CO2H)2 under similar conditions (no BnOH) are also reported. The dianilines were found to be capable of the ROP of δ-VL (but not ε-CL), whilst anthranilic acid outperformed 2-aminoterephthalic acid for both ε-Cl and δ-VL.
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