text stringlengths 68 1.08k |
|---|
## Introduction
N-heterocyclic carbenes (NHCs), first described in 1991, 1 have found many applications. 2 There are several structural features that allow the tuning of their electronic properties. Ring size, the adjacent heteroatoms, N -substituents, and the backbone can be modified. Changing one or more structural... |
## Introduction
‡ These authors contributed equally to this work.
Synthesis, characterization, and biomedical evaluation of ethylene-bridged tetra-NHC Pd(II), Pt(II) and Au(III) complexes, with apoptosis-inducing properties in cisplatin-resistant neuroblastoma cells †
Wolfgang R. E. Büchele, ‡ a Tim P. Schlachta, ‡ ... |
## Introduction
Synthesis and characterization of the fi first two cyclic ethylene-bridged tetradentate NHC ligands, with an unsaturated (imidazole) and saturated backbone (2-imidazoline), are described. Complexes of both ligands containing palladium(II) have been obtained. For platinum(II) and gold(III), only the uns... |
## Introduction
Our group has developed several bidentate and cyclic tetradentate NHC ligands. The respective transition metal complexes have been applied e.g. in medicinal chemistry 6,7 and epoxidation catalysis. 3 While the bidentate ligands can form open-chain tetracarbene complexes, 8,9 the tetradentate ligands gi... |
## Introduction
Fig. 1 Tetracarbene ligand precursor a and derived transition metal complexes b -f .
In this study, the scope of multidentate NHC ligands is extended with an ethylene-bridged bisimidazolinium ligand precursor and two cyclic ethylene-bridged tetradentate NHC ligands, with an unsaturated (imidazole) and... |
## Introduction
Especially the two new macrocyclic ligand precursors are intended to lay the foundation for electronic comparisons induced by the diff erent backbone in future studies. The unsaturated backbone of the imidazole moiety causes partial aromaticity, increasing NHC stability by ca. 100 kJ mol -1 . 19 -21 A ... |
## Introduction
## Results and discussion
The synthesis of a saturated macrocyclic ligand precursor similar to c , but containing 2-imidazoline moieties instead of imidazole, calix[4]imidazolinium, was pursued parallel to the synthesis of the other ligand precursors. However, the synthesis was not successful with the... |
## Synthesis and characterization of H2L3
## Synthesis and characterization of H4L5/6 and H4L8/L9
For the preparation of H4L5/6 and H4L8/9 , a slightly modified literature procedure for similar macrocycles was used (Fig. 3). 10 Ring closure to form the macrocyclic imidazolium salt a is commonly achieved with CH2(OTf)... |
## Synthesis and characterization of H4L5/6 and H4L8/L9
The synthesis of H4L5 and H4L8 yields a mixture of a 20membered macrocycle (87% H4L5 and 90% H4L8 , as determined by NMR), consisting of four imidazole (C[4]) units, and a 30-membered macrocycle (13% H4L5 , 10% H4L8 ) consisting of six imidazole (C[6]) units (see... |
## Synthesis and characterization of H4L5/6 and H4L8/L9
Relative to a , all signals of H4L5 and H4L8 are up eld shi ed, indicating a higher electronic density due to the +I eff ect of the ethylene bridge leading to an increased shielding eff ect in the NMR. 10,26 The higher up eld shi of H4L5 compared to H4L8 can ... |
## Synthesis and characterization of H4L5/6 and H4L8/L9
Unlike in 1 H-NMR, each individual 13 C signal of H4L8 in DMSO-d6 is in the same range as the signals obtained for the macrocyclic compound a . 10 However, in case of H4L5 , opposite to the 1 H-NMR, the C2 carbon resonance at 159.16 ppm is down eld shi ed compa... |
## Synthesis and characterization of H4L5/6 and H4L8/L9
Salt metathesis of the formed macrocyclic salts can be performed with NH4PF6 to increase the solubility in organic solvents and as additional puri cation step. 3,30 Thus, an anion exchange in water towards PF6 -is conducted with H4L5 and H4L8 , resulting in H4L6... |
## Synthesis and characterization of complexes (Pd/PtL3, PdL5/6, Pd/PtL8, Pd/AuL9)
A well-established route to obtain NHC complexes is to convert the corresponding imidazolium salts with group 10 metal acetates. In this reaction, the acetate serves as an internal base capable of deprotonating imidazoliumand imidazolini... |
## Synthesis and characterization of complexes (Pd/PtL3, PdL5/6, Pd/PtL8, Pd/AuL9)
base at diff erent temperatures were tested without success. A possible problem might be the stability of the Ag I -complex. Another issue might be hydrolysis of imidazolines under acidic and basic conditions. 36,37 It has been proposed... |
## Synthesis and characterization of complexes (Pd/PtL3, PdL5/6, Pd/PtL8, Pd/AuL9)
The absence of the acidic imidazolinium proton signal and appearance of characteristic carbene carbon signals con rms the successful formation of PdL3 and PtL3 . Unfortunately, despite several attempts, a clean elemental analysis for P... |
## Synthesis and characterization of complexes (Pd/PtL3, PdL5/6, Pd/PtL8, Pd/AuL9)
The carbene carbon signal of PdL3 at 194.29 ppm in DMSOd6 [ PtL3 ; 188.38 ppm in CD3CN], is surprisingly down eld shi ed compared to other Pd(II) bis-NHCs reported in literature. 39,40 Due to the theoretically stronger s -donation of ... |
## Synthesis and characterization of complexes (Pd/PtL3, PdL5/6, Pd/PtL8, Pd/AuL9)
structure. Two L3 ligands coordinate to the Pd center, resulting in an openchain tetracarbene complex of similar geometry like the cyclic complex e . 34 The Pd -C (2.039 Å, 2.038 Å) distances are in good accord with palladium(II) NHC co... |
## Synthesis and characterization of complexes (Pd/PtL3, PdL5/6, Pd/PtL8, Pd/AuL9)
Fig. 4 General synthesis of Pd/PtL3 .
Fig. 5 ORTEP-style representation of the cationic fragment of complex PdL3 . Hydrogen atoms and hexa fl uorophosphate anions are omitted for clarity. Thermal ellipsoids are shown at a 50% probabili... |
## Complex PdL5/6 and PdL8/9
Since H4L5 and H4L8 are quite similar to other macrocycles ( a ), it seemed suitable to synthesize PdL5 and PdL8 according to alike compounds via the direct metalation route. 32 Therefore, H4L8 was first converted with Pd(OAc)2 in a mixture of dry DMSO/MeCN (1 : 1) at 40 °C for 16 h. 34 Ho... |
## Complex PdL5/6 and PdL8/9
. The yield of the imidazolinylidene tetracarbene complex could be increased to 46%, by using H4L6 instead of H4L5 , resulting in PdL6 . |
## Complex PdL5/6 and PdL8/9
Fig. 6 ORTEP-style representation of the cationic fragment of complex PtL3 . Hydrogen atoms and hexa fl uorophosphate anions are omitted for clarity. Thermal ellipsoids are shown at a 50% probability level. Selected bond lengths (Å) and angles (°): Pt1 -C1 2.0337 (18); Pt1 -C7 2.039 (6), C... |
## Complex PdL5/6 and PdL8/9
Again, the absence of the acidic position 2 proton signals in the 1 H-NMR and appearance of the carbene carbon peaks con rm the formation of Pd(II) carbene complexes. The observed chemical shi of PdL8 is in the typical range of Pd(II) tetra-NHC compounds and indicates the formation of a ... |
## Complex PdL5/6 and PdL8/9
is a general phenomenon. 38,41,42 The uncertainty of a 13 C-NMR measurement is expected to be below 0.1 ppm; by using three times the weighted standard deviation, a diff erence of >0.4 ppm is required for a significant diff erence that exceeds the statistic uncertainty. 3,48 Therefore, ... |
## Complex PdL5/6 and PdL8/9
not met here, and apparently other factors may play a role, as already observed with PdL3 and PtL3 . Therefore, further investigations on this subject, e.g. by means of DFT calculations, have to be carried out, since only conjectures can be made with the present analytical data. The elemen... |
## Complex PdL5/6 and PdL8/9
fashion with C -Pd -C angles deviating from 180° by ∼ 8°, thus li ing the metal slightly above the carbene carbon atom plane (Fig. 8). However, due to the C2-bridge, the ligand is strongly bent (C5 -Pd1 -C5\_b = 98.97°) and adopts a crisp-shape, while tilting the imidazole rings 53.62° in... |
## Complex PdL5/6 and PdL8/9
Fig. 8 ORTEP-style representation of the cationic fragment of complex PdL9 . Hydrogen atoms and hexa fl uorophosphate anions are omitted for clarity. Thermal ellipsoids are shown at a 50% probability level. Selected bond lengths (Å) and angles (°): C1 -Pd 2.019(2), C1 -Pd1 -C1\_b 172.03(12... |
## Complex PdL5/6 and PdL8/9
| Compound | PdL3 | PtL3 | PdL9 |
|-------------------------------|---------------|---------------|--------|
| M - C carbene [Å] | 2.038 j 2.039 | 2.033 j 2.039 | 2.019 |
| C carbene - M - C carbene [°] | 180 | 180 |... |
## Complex PtL8
Applying the same reaction conditions and work-up methods to Pt(MeCN)2Cl2 instead of Pd(OAc)2 results in the formation of PtL8 (25%,Fig. 7). The absence of acidic proton signals in the 1 H-NMR and the appearance of the carbene 13 C-peak at 159.39 ppm in CD3CN con rms the formation of the respective Pt(... |
## Complex PtL8
the discussed analytical data strongly support a similar structure compared to PdL8 and similarly structured tetracarbene ligand. 6,34 |
## Complex AuL9
For the synthesis of AuL9 (Fig. 7), the same reaction conditions were applied as reported in the literature for similar complexes. 51 Therefore, H4L8 was converted with KAuCl4 and NaOAc in dry DMSO under exclusion of light at 100 °C for 5 h. A er the work-up, including an ion exchange to PF6 -as a puri... |
## Complex AuL9
at 7.47 ppm and the bridge protons as two multiplets in close proximity at 4.83 and 4.71 ppm. Both elemental analysis 52 and HR-ESI-MS are in agreement with the composition [ Au(L15) ](PF6)3. Although no single crystals suitable for SC-XRD were obtained, the discussed analytical data strongly support t... |
## Biological evaluation
## Induction of apoptosis as cell death type
PdL3 , PdL8 , AuL9 and their respective protonated ligand precursors were tested for their apoptotic eff ects on Nalm-6 cells (human B cell precursor leukemia cell line) and SK-N-AS cells (human neuroblastoma cell line) at diff erent concentrations ... |
## Induction of apoptosis as cell death type
Fig. 9 (A) AuL9 induces apoptosis in SK-N-AS cells. The cells were treated with diff erent concentrations of AuL9 and incubated for 96 h. Nuclear DNA fragmentation was analyzed. (B) To exclude unspeci fi c cytotoxic eff ects, such as necrotic cell death, the viability of SK... |
## Induction of apoptosis as cell death type
To exclude necrotic eff ects of AuL9 , lactate dehydrogenase (LDH) leakage from SK-N-AS cells a er 2 h incubation with AuL9 was measured. LDH is released from the cell in case of necrosis and can be detected in the cell culture medium in case of loss of cell integrity and ... |
## Induction of apoptosis as cell death type
In addition to apoptosis induction, it was tested whether AuL9 can inhibit the proliferation of malignant cells. For this purpose, SK-N-AS cells were incubated with diff erent concentrations of AuL9 for 48 hours. The proliferation inhibition was determined by comparing the ... |
## Induction of apoptosis as cell death type
To further characterize the role of mitochondria in AuL9 -induced apoptosis, the apoptosis pathway mediated by reactive oxygen species (ROS) was investigated. Therefore, N -acetylcysteine (NAC) as a known ROS inhibitor and H2O2, which belongs to the ROS, as a positive contr... |
## Induction of apoptosis as cell death type
## Overcoming cisplatin resistance
Cisplatin is a well-known chemotherapeutic agent for the treatment of many diff erent types of cancer. 54 The development of resistance in tumor cells is a major problem in therapy and is usually the limiting factor in the cure of cancer ... |
## Overcoming cisplatin resistance
Fig. 10 (A) The mitochondrial membrane potential in SK-N-AS cells was impaired by AuL15 treatment, which implicates mitochondrial pathway involvement in apoptosis induction. The mitochondrial membrane potential was measured by fl ow cytometric analysis in SKN-AS cells after 48 h of i... |
## Overcoming cisplatin resistance
by fl ow cytometric analysis. Values are mean% of apoptotic cells ± SD ( n = 3); * : p < 0.05 vs. DMSO, t -test. |
## Overcoming cisplatin resistance
Fig. 11 SK-N-AS and SK-N-AS cisplatin resistant cells were treated with diff erent concentrations of AuL15 and incubated for 96 h. It is shown that AuL9 was also eff ective in inducing apoptosis in cisplatin resistant cells, thus overcoming resistance. 8.25 m Mcisplatin has been used... |
## Overcoming cisplatin resistance
Therefore, it is of great importance for drug development that new agents are able to overcome cytostatic drug resistance. In addition to SK-N-AS cells, AuL9 was tested on cisplatin resistant SK-N-AS cells and cisplatin resistance overcoming could be demonstrated (Fig. 11). In a prev... |
## Conclusion and outlook
A synthetic approach to a calix[4]imidazolinium macrocycle as saturated analog to a is presented. The synthesis of two new macrocyclic ligand systems, being bridged by ethylene groups and containing imidazoline ( H4L5/6 ) and imidazole moieties ( H4L8 / 9 ) are discussed. In addition, a novel ... |
## Conclusion and outlook
silver oxide is used in combination with the metal precursor and an excess of sodium acetate as a mild base, resulting in the corresponding complexes. Furthermore, the complexes PdL3 , PdL8 , AuL9 and their respective ligands were tested for their ability to induce apoptosis on Naml-6 and SK-... |
## Conclusion and outlook
, for example identi cation of molecular targets that are involved in the AuL9 induced apoptosis, as well as the selectivity for cancer cells. |
## Experimental section
## General procedures and analytical methods |
## General procedures and analytical methods
Unless otherwise stated, all manipulations were performed under normal atmosphere without dried and degassed chemicals. All syntheses regarding the complexes were conducted under the exclusion of light. Every work-up was performed under normal atmosphere without dried and d... |
## General procedures and analytical methods
over molecular sieves (3 Å). The procedures for novel compounds obtained during the synthetic approaches to the saturated macrocyclic ligand precursor, containing 2imidazoline moieties instead of imidazole, calix[4]imidazolinium, (2-imidazoline, N -benzyl-2-imidazoline, 3,3... |
## General procedures and analytical methods
N 1 , N 1 , N 2 , N 2 -tetrabenzylethane-1,2-diamine, tert -butyl (2-aminoethyl)carbamate, tert -butyl 2-imidazoline-1-carboxylate) are stated in the ESI. † N -Benzylethylenediamine ( 12 ), 57 -59 ethylenebis(tri uoromethanesulfonate) ( 4 ), 60 1,1 0 -ethylene-di-2imidazol... |
## General procedures and analytical methods
ionization mass spectrometry (ESI-MS) data were acquired on a Thermo Fisher Ultimate 3000 and with higher resolution (HR-ESI-MS) on Exactive Plus Orbitrap from Thermo Fisher. |
## Synthetic procedures
Alkylbisimidazoline diiodide (2). 1 (5.00 g, 30.0 mmol, 1.00 eq.) is dissolved in MeCN (300 mL) and MeI (213 g, 1.50 mol, 50.0 eq.) is added. The resulting reaction mixture is heated to re ux for 4 h. A er cooling to ambient temperature, all volatile compounds are removed in vacuo . The result... |
## Synthetic procedures
C H2 -C H2), 35.08 ( C H3). Elemental analysis: for C10H20I2N4 (%) anal. calc.: C: 26.68, H: 4.48, N: 12.45, found: C: 26.66, H: 4.48, N: 12.39. |
## Synthetic procedures
Alkylbisimidazolinium hexa uorophosphate (H2L3). 2 (100 mg, 222 m mol, 1.00 eq.) is dissolved in H2O (1 mL) and added to a solution of NH4PF6 (217 mg, 1.33 mmol, 6.00 eq.) in H2O (1 mL). The resulting white precipitate is collected, washed three times with H2O (2 mL, 2 mL, 1 mL) and dried subs... |
## Calix[4]( -Et -Et -)imidazoliniumtri uoromethanesulfonate
(H4L5). 1 (1.00 g, 6.17 mmol, 2.00 eq.) is dissolved in dry MeCN (1.5 L), cooled to -45 °C and a solution of 4 (2.02 g, 6.20 mmol, 2.01 eq.) in dry MeCN (50 mL) is added dropwise over 6 h. A er the addition, the reaction mixture is stirred for 72 h at ambie... |
## Calix[4]( -Et -Et -)imidazoliniumtri uoromethanesulfonate
(ppm) = -77.74 (C F 3). Elemental analysis for C24H36N8O12F12S4 (%) anal. calc.: C 29.27; H 3.68; N 11.38; S 13.02 found: C 29.37; H 3.67; N 11.01; S 13.12. |
## Calix[4]( -Et -Et -)imidazoliniumtri uoromethanesulfonate
## Calix[4]( -Et -Et -)imidazoliniumhexa uorophosphate
(H4L6). H4L5 (300 mg, 304 m mol, 1.00 eq.) is dissolved in H2O (50 mL) and added to a solution of NH4PF6 (223 mg, 1.37 mmol, 4.50 eq.) in H2O (50 mL). The resulting white precipitate is collected, was... |
## Calix[4]( -Et -Et -)imidazoliniumhexa uorophosphate
(m, 16H, C H 2,(bridge)/C H 2,(backbone) ). 19 F-NMR (376 MHz, CD3CN): d (ppm) = -72.45 (d, 1 J P -F = 713 Hz, PF6 -). ESI-MS: m / z = calc. for [ H4L6 -PF6 -] + : 823.20 ([M -PF6 -] + ); found: 822.94; calc. for [ H4L6 -2PF6 -] + : 339.11 ([ H4L6 -2PF6 -] + ); f... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
(H4L8). 7 (1.00 g, 6.17 mmol, 2.00 eq.) is dissolved in dry MeCN (1.5 L), cooled to -30 °C and a solution of 4 (2.02 g, 6.20 mmol, 2.01 eq.) in dry MeCN (100 mL) is added dropwise over 5 h. A er the addition, the reaction mixture is stirred for 72 h at ambien... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
(C F 3). 1 H-NMR (400 MHz, DMSO-d6) d (ppm) = 9.00 (t, 4 J = 1.7 Hz, 4H, N -C H -N), 7.57 (d, 4 J = 1.6 Hz, 8H, C H ), 4.74 (s, 16H, C H 2). 13 C-NMR (101 MHz, DMSO-d6) d (ppm) = 137.08 (N -C H -N), 123.28 (H C ] C H), 120.66 (q, 1 J 19F -13C = 320 Hz, OTf -)... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Calix[4]( -Et -Et -)imidazoliumhexa uorophosphate (H4L9). H4L8 (3.20 g, 3.28 mmol, 1.00 eq.) is dissolved in H2O (300 mL) and added to a solution of NH4PF6 (3.20 g, 19.66 mmol, 6.00 eq.) in H2O (50 mL). The resulting white precipitate is collected, washed th... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Pd[C Et Cimi(Me)2C Et Cimi(Me)2]hexa uorophosphate (PdL3). Ag2O (150 mg, 648 m mol, 1.05 eq.) is added to a solution of H2L3 (300 mg, 617 m mol, 1.00 eq.) and NaOAc (202 mg, 2.47 mmol, 4.00 eq.) in dry MeCN (15 mL) and stirred for 1 h at ambient temperature,... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
A er drying in vacuo , the titled compound PdL3 is obtained as an o ff -white solid (140 mg, 178 m mol, 29%). Single crystals suitable for SC-XRD were obtained by slow diff usion of Et2O into MeCN solution of PdL3 . 1 H-NMR (400 MHz, CD3CN) d (ppm) = 4.32 -4... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Elemental analysis: for C20H36F24N8P4Pd1 (%) anal. calc.: C: 30.60, H: 4.62, N: 14.28, found: C: 30.93, H: 4.55, N: 14.14, S: 0.00. HR-ESI-MS: m / z [ PdL3 -2PF6 -] 2+ calc.: 247.1044, found: 247.1039, [ PdL3 -PF6 -] + calc.: 639.1735, found: 639.1720. |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Pt[C Et Cimi(Me)2C Et Cimi(Me)2]hexa uorophosphate (PtL3). Ag2O (150 mg, 648 m mol, 1.05 eq.) is added to a solution of H2L3 (300 mg, 617 m mol, 1.00 eq.) and NaOAc (202 mg, 2.47 mmol, 4.00 eq.) in dry MeCN (15 mL) and stirred for 1 h at ambient temperature,... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
A er drying in vacuo , the titled compound PtL3 is obtained as an o ff -white solid (23 mg, 26 m mol, 4%). Single crystals suitable for SC-XRD were obtained by slow diff usion of Et2O into MeCN solution of PtL3 . Note; a clean EA could not be obtained, and t... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Pd[(cC Et CC Et Cimi)OTf] (PdL5). Ag2O (155 mg, 670 m mol, 2.20 eq.) is added to a solution of H4L5 (300 mg, 305 m mol, 1.00 eq.) and NaOAc (200 mg, 2.42 mmol, 8.00 eq.) in dry MeCN/DMSO (12 mL 1 : 1) and stirred for 1 h at ambient temperature, followed by th... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
washed with Et2O (3 × 5 mL) and redissolved in MeCN (5 mL). A er puri cation [3 times dissolving in MeCN (4 mL) and precipitating with Et2O ( ∼ 15 mL)] and removing all volatile compounds in vacuo , the titled compound PdL5 is obtained as an o ff -white sol... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Pd[(cC Et CC Et Cimi)PF6] (PdL6). PdL6 is synthesized analog to PdL5 ; by converting H4L6 (230 mg, 238 m mol, 1.00 eq.) with Ag2O (121 mg, 522 m mol, 2.20 eq.) in dry MeCN (4 mL) while stirring for 1 h at ambient temperature, followed by the addition of NaOAc... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
ESI-MS: m / z = calc. for [ PdL6 -PF6 -] + : 635.14 ([M -PF6 -] + ); found: 635.21. HR-ESI-MS: m / z [ PdL6 -2PF6 -] 2+ calc.: 245.0887, found: 245.0890, [ PdL6 + H2O -2PF6 -] 2+ calc.: 254.0940, found: 254.0944, [ PdL6 -PF6 -] + calc.: 635.1422, found: 635.1... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Pd[(cC Et CC Et C)OTf] (PdL8). Ag2O (74.7 mg, 322 m mol, 1.05 eq.) is added to a solution of H4L8 (320 mg, 307 m mol, 1.00 eq.) and NaOAc (202 mg, 2.46 mmol, 4.00 eq.) in dry MeCN (15 mL) and stirred for 1 h at ambient temperature, followed by the addition of... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
, the titled compound PdL8 is obtained as an o ff -white solid (119 mg, 153 m mol, 50%). 1 H-NMR (400 MHz, CD3CN) d (ppm) = 7.20 (s, 8H, C H ), 5.02 -4.93 (m, 8H, C H 2), 4.47 -4.39 (m, 8H, C H 2). 13 C-NMR (101 MHz, CD3CN) d (ppm) = 165.84 (N -C -N), 123.77 ... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
241.0574, found: 241.0570, [ PdL8 -OTf -] + calc.: 631.0674, found: 631.0658.
Pd[(cC Et CC Et C)PF6] (PdL9). PdL8 (95 mg, 122 m mol, 1.00 eq.) is dissolved in H2O (35 mL), a er the addition of NH4PF6 (50.0 mg, 305 m mol, 2.5 eq.) a white precipitate is coll... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Pt[(cC Et CC Et C)OTf] (PtL8). Ag2O (209 mg, 900 m mol, 2.20 eq.) is added to a solution of H4L8 (400 mg, 410 m mol, 1.00 eq.) and NaOAc (202 mg, 2.46 mmol, 4.00 eq.) in dry MeCN (30 mL) and stirred for 1 h at ambient temperature, followed by the addition of ... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
titled compound PtL8 is obtained as an o ff -white solid (90 mg, 103 m mol, 25%). 1 H-NMR (400 MHz, CD3CN) d (ppm) = 7.19 (s, 8H, C H ), 5.11 -4.94 (m, 8H, C H 2), 4.50 -4.38 (m, 8H, C H 2). 1 H-NMR (400 MHz, DMSO-d6) d (ppm) = 7.49 (s, 8H, C H ), 5.06 -4.97 ... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
Au[(cC Et CC Et C)PF6] (AuL9). H4L8 (500 mg, 458 m mol, 1.00 eq.), KAuCl4 × 2H2O (209 mg, 505 m mol, 1.05 eq.), and NaOAc (197 mg, 2.41 mmol, 5.00 eq.) are suspended in dry DMSO (5 mL). The resulting reaction mixture is stirred for 5 h at 100 °C and ltered a... |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
C H 2), 4.76 -4.66 (m, 8H, C H 2). 13 CNMR (101 MHz, CD3CN) d (ppm) = 146.03 (N -C H -N), 125.92 (H C ] C H), 48.58 ( C H2 -C H2). Elemental analysis for C20H24AuF18N8P3 × 0.1 MeCN (%) anal. calc.: C 24.62; H 2.70; N 11.11; |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
S 0.00 found: C 24.82; H 2.78; N 11.15; S 0.57. HR-ESI-MS: m / z [ AuL9 -3PF6 -] 3+ calc.: 191.0591, found: 191.0587, [ AuL9 -PF6 -] + calc.: 863.1068, found: 863.1038. |
## Calix[4]( -Et -Et -)imidazoliumtri uoromethanesulfonate
## Confl icts of interest
There are no con icts to declare.
## Acknowledgements
All authors thank Prof. Dr T. Simon (University Cologne) for providing the SK-N-AS cell line, Dr Seeger for providing the Nalm-6 cell line. A. Prokop thanks the Dr. Kleist Fou... |
No dataset card yet
- Downloads last month
- 40