| 93% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate Reflux; |
|
| 88% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Reflux; |
|
| 86% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 0.5h; Reflux; Inert atmosphere; Schlenk technique; |
Synthesis of 2,9-dicarbaldehyde-1,10-phenanthroline
The ligand was synthesized from a modified literature procedure [52]: To a solution of selenium oxide (2.26 g, 20.41 mmol) in deionized water (5 mL) and 1,4-dioxane (70 mL), 2,9-dimethyl-1,10-phenanthroline (2.00 g, 9.60 mmol) in 1,4-dioxane (20 mL) was added in a dropwise manner. The reaction mixture was refluxed for 0.5 h, during which the color of the reaction mixture changed from yellow to reddish brown with black deposits. Upon cooling to room temperature, the brown solids were collected by suction filtration and washed with Et2O (10 mL × 3). These solids were further purified by recrystallization with warm CHCl3and allowed to cool and stand overnight. Yellowish orange solids were collected by suction filtration and washed with Et2O (10 mL × 3) to give 2,9-dicarbaldehyde-1,10-phenanthroline.1H-NMR signals are consistent with that of the literature reported [50]. Yield: 1.95 g, 86%. |
| 85% |
With selenium(IV) oxide In 1,4-dioxane for 0.166667h; Heating; microwave; |
|
| 85% |
With selenium(IV) dioxide In 1,4-dioxane for 2h; Reflux; |
|
| 85% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 0.5h; Reflux; |
|
| 85% |
With selenium(IV) dioxide In 1,4-dioxane at 60 - 100℃; for 14.5h; |
|
| 85% |
With selenium(IV) dioxide In 1,4-dioxane at 85℃; for 6h; |
|
| 85% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate at 20℃; for 0.333333h; |
2.2. Procedure for synthesis of compound 2
Neocuproine (14.4 mmol, 1 equiv., 3 g) was dissolved in dioxane(50 mL) and water (2 mL), and the resulting solution was stirred for20 min. at room temperature. A suspension of selenium dioxide(64.8 mmol, 4.5 equiv., 7.19 g) in a mixture of dioxane (130 mL)and water (5.2 mL) was then added, and the color changed frombrown to white. The resulting suspension was refluxed for 24 h,and then the black colored precipitate (selenium metal) was filteredwhile hot. The resulting solution was cooled and the resultingprecipitate was filtered to give the desired compound whichwas purified by crystallization from acetone. |
| 81% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Reflux; |
|
| 81.75% |
With selenium(IV) dioxide In 1,4-dioxane for 12h; |
2.2.1. Synthesis of 1,10-phenanthroline-2,9-dicarbaldehyde
1,10-Phenanthroline-2,9-dicarboxaldehyde was synthesized accordingto a previously reported method [36-40]. To a double-mouthedround bottom flask, 30 mL of a dioxane solution dissolved in seleniumdioxide (4.5 g, 40.55 mmol) was added and placed in a water bath. Witha constant-pressure drop funnel, 100 mL of dioxane solution dissolved inneocopper reagent (3 g, 14.40 mmol) was added drop by drop to thedouble-bottomed flask. After 12 h in the water bath reaction, while hotfilter out the tar and selenium collection filtrate, the filtrate was yellow.When the filtrate was cooled, a large number of yellow precipitates weregenerated, namely 1,10-phenanthroline-2,9-dicarboxaldehyde crudeproduct. After filtering out the crude product, it was collected and dissolvedin benzene, to which n-hexane was added for recrystallization.Finally, the resulting product was filtered and dried to obtain a goldenyellow needle-like solid. Golden yellow needle-like solid 3.1313 g, yield:81.75%. M.p.: 238-240 C. Anal. Calcd. for C14H8N2O2 (%): C, 71.18; H,3.41; N, 11.86. Found: C, 71.29; H, 3.25; N, 11.62. 1H NMR (500 MHz,DMSO) δ 10.36 (d, J = 0.8 Hz, 1H), 8.80 (dd, J = 8.2, 0.8 Hz, 1H), 8.32(d, J = 8.2 Hz, 1H), 8.29 (s, 1H). |
| 80.56% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 3h; Reflux; |
2.1.1 2,9-Dicarboxylic acid-1,10-phenanthroline
Selenium oxide (13.5 g, 0.12 mol) and 2,9-dimethyl-1,10-phenanthroline (5 g, 0.02 mol) were added into a mixture of1,4-dioxane (320 mL) and ultra-pure water (50 mL) in a500 mL of round-bottom flask. The reaction remained underreflux for 3 h and filtered while hot, then the filtrate was leftto cool. Golden product, 2,9-dicarbaldehyde-1,10-phenanthroline(4.62 g, 80.56%), was obtained after another filtration.Then, 2,9-dicarbaldehyde-1,10-phenanthroline (3 g,0.013 mol) was added into concentrated nitric acid (65%, 60 mL). After refluxing for 3 h, the solution was cooled bypoured onto the solid ice and the crude product was separatedout gradually. The crude product was filtered to get the solidproduct and dried before the next step |
| 80% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Reflux; |
|
| 74% |
With selenium(IV) dioxide In 1,4-dioxane Inert atmosphere; |
|
| 73% |
With selenium(IV) dioxide In 1,4-dioxane at 20℃; for 2h; Reflux; |
|
| 72% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 0.666667h; Reflux; |
|
| 72% |
With selenium(IV) dioxide In 1,4-dioxane for 0.666667h; Reflux; |
|
| 72% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Reflux; |
|
| 70% |
With selenium(IV) oxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Heating; |
|
| 70% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Reflux; |
|
| 70% |
With selenium(IV) dioxide In 1,4-dioxane for 2h; Reflux; |
|
| 70% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate Reflux; |
|
| 69% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate Reflux; |
2,9-dicarbaldehyde-1,10-phenanthroline.
To a solution of 5.65 g (50.9 mmol) of selenium dioxide in 150 mL dioxane and 10 mL water was addeddropwise a solution of 5.0 g (24.0 mmol) 2,9-dimethyl-1,10-phenanthroline in 100 mL dioxane. Themixture was heated to reflux under magnetic stirring.The disappearance of 2,9-dimethyl-1,10-phenanthrolinewas followed by TLC with dichloromethane/methanol (8/2 v/v) as eluent. Thereaction was stopped when complete disappearance of the reactant was achieved (ca. 4 h).The mixture was filtrated on Celite while hot, the filtrate was allowed to cool and a brownsolid precipitated. It was collected by filtration, washed with dioxane and dried over vacuumto yield a brown solid (3.90 g, 69% yield). The product was engaged in the next step without further purification. |
| 67.1% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 1h; Reflux; |
|
| 67.6% |
With selenium(IV) dioxide In 1,4-dioxane at 110℃; for 2h; |
|
| 63% |
With selenium(IV) dioxide In dimethyl sulfoxide for 3h; Inert atmosphere; Reflux; |
|
| 50% |
With selenium(IV) oxide; lithium hydroxide monohydrate In 1,4-dioxane for 0.25h; Heating; |
|
| 48% |
With iodine; tert-Butyl iodide; trifluoroacetic acid In dimethyl sulfoxide at 148℃; for 2h; |
|
| 47% |
With selenium(IV) oxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Heating; |
|
| 46.93% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Reflux; |
2.2.1. 2,9-dicarbaldehyde-1,10-Phenanthroline
This compound was prepared according to a literature method [34]with a slight modification. Selenium oxide (1.87 g, 0.05 mol) was addedinto a mixture of 1,4-dioxane (150 mL) and deionized water (10 mL) in a500 mL three necked-flask. After heating to refllux, a solution of 2,9-dimethly-1,10-phenanthroline (1.67 g, 0.024 mol) in 1,4-dioxane(100 mL) was added drop wise into the flask for over 10 min. The reactionwas allowed to run under reflluxf or 2 h then reaction was stoppedand the mixture was filtered while hot, the filtrate was allowed to cool atroom temperature. A yellow needle solid was obtained from filtrate afterfiltration. The solid was used directly for following reaction without anyfurther purification. Yield: 0.890 g, 46.93%. The structure wasconfirmed by 1H NMR. |
| 45% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 2h; Reflux; |
|
| 43% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 3h; Reflux; |
|
| 34% |
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate Reflux; |
|
|
With selenium(IV) oxide In 1,4-dioxane |
|
|
With selenium(IV) oxide In 1,4-dioxane for 3h; Heating; |
|
|
With selenium(IV) oxide In 1,4-dioxane for 2h; Heating; |
|
|
With selenium(IV) dioxide In 1,4-dioxane |
|
|
With selenium(IV) dioxide |
|
|
With selenium(IV) dioxide In 1,4-dioxane |
|
|
With selenium(IV) dioxide |
|
|
With selenium(IV) dioxide |
|
|
With selenium(IV) dioxide |
|
|
With selenium(IV) dioxide In 1,4-dioxane |
|
|
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate for 2.16667h; Reflux; |
|
|
With selenium(IV) dioxide In 1,4-dioxane |
Synthesis of 1,10-phenanthroline-2,9-dicarboxylic acid bis-[(2-methoxyphenyl)amide] (1)
General procedure: The oxidation of 2,9-dimethyl-1,10-phenanthroline with SeO2 in dioxane yielded 1,10-phenanthroline-2,9-dicarboxaldehyde which was further oxidized to 1,10-phenanthroline-2,9-dicarboxylic acid using concentrated HNO3.29 1,10-Phenanthroline-2,9-dicarboxylic acid (0.500 g, 1.86 mmol) was refluxed for two hours in excess SOCl2 (12 ml, 0.168 mol) and a drop of DMF was added in catalytic amount. SOCl2 was then removed at a reduced pressure resulting in diacyl chloride as pale yellow residue to which was added K2CO3 (0.567 g, 4.11 mmol), 2-methoxy aniline (0.506 g,4.11 mmol) and TBAHSO4 in catalytic amount and 25 ml of freshly dry distilled acetonitrile. The contents were refluxed until TLC monitoring indicated completion of the reaction. The contents were filtered and the solvent was vacuum evaporated to yield crude yellow solid. Recrystallization of crude product from mixture of methanol and chloroform resulted in the formation of pure amide. |
|
With selenium(IV) dioxide In 1,4-dioxane for 4h; Reflux; |
|
|
With selenium(IV) oxide |
|
|
With selenium(IV) oxide In 1,4-dioxane; lithium hydroxide monohydrate |
|
| 0.6% |
With selenium(IV) dioxide In 1,4-dioxane Heating; |
|
|
With selenium(IV) dioxide In 1,4-dioxane for 1h; Heating; |
|
|
With selenium(IV) oxide In 1,4-dioxane for 0.5h; Reflux; |
|
|
With selenium(IV) dioxide In 1,4-dioxane Reflux; |
|
|
With selenium(IV) dioxide In 1,4-dioxane Reflux; Inert atmosphere; |
|
|
With selenium(IV) dioxide In 1,4-dioxane |
|
|
With selenium(IV) dioxide In 1,4-dioxane for 5h; Reflux; |
First step
A reaction mixture of 2,9-dimethyl-1,10-phenanthroline hemihydrate (10 mM)and selenium dioxide (10 mM) was placed in 100 mL of dioxane in a 250-mL round bottom(RB) flask. The mixture was manually stirred and allowed to reflux in a wax bath for 5 h. Thehot solution was filtered and a yellow-orange product separated from the filtrate. |
|
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate |
|
|
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate at 100℃; for 2h; |
|
|
With selenium(IV) dioxide; lithium hydroxide monohydrate In 1,4-dioxane at 80℃; |
2.1. Synthesis
General procedure: The V-shaped phenanthroline-based hexacatenars in which 1,10-phenanthroline was substituted on 2,9- positions with two cyanovinyl units were prepared according to Scheme 1. 1,10-phenanthroline-2,9-dicarbaldehyde 2[27] was synthesized by oxidationof 2,9-dimethyl-1,10-phenanthroline in the presence of SeO2 in 1,4-dioxane. 4-Hydroxybenzyl cyanide was etherified with benzylchlorides in the presence of K2CO3 in DMF to yield the key intermediate compounds 5/n.[22d,28] Compound 2 was reacted with 5/n under Knoevenagel reaction condition to yield the target compounds Phe/n. All the intermediate compounds and target compounds were purified by column chromatography, the chemical structures were determined by NMR spectra and element alanalysis. The detailed synthetic procedure and corresponding data were described in the ESI. Although some 3,8-disubstituted 1,10-phenanthroline-based polycatenar mesogens had been synthesized using Suzuki and Sonogashira coupling,[12] these Phe/n were the first examples of V-shaped hexacatenars which were synthesized by Knoevenagel reaction in high yields. |
|
With selenium(IV) dioxide In 1,4-dioxane; lithium hydroxide monohydrate Reflux; |
|
|
With selenium(IV) dioxide In 1,4-dioxane at 101.84℃; |
|
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