KR20200041551A - Novel imidazole-based derivatives having excellent fluorescence properties and synthesizing method thereof - Google Patents

Abstract

The present invention relates to: an imidazole derivative represented by chemical formula 1, and having excited-state intermolecular proton transfer (ESIPT) characteristics; and a manufacturing method thereof. In the chemical formula 1, X is halogen. The imidazole derivative according to the present invention can be usefully used in organic electroluminescent devices, chemical sensors, solar energy concentrators, ultraviolet stabilizers, and the like.

Description

A novel imidazole derivative with excellent fluorescence properties and its manufacturing method {NOVEL IMIDAZOLE-BASED DERIVATIVES HAVING EXCELLENT FLUORESCENCE PROPERTIES AND SYNTHESIZING METHOD THEREOF}

The present invention relates to a novel imidazole derivative and a method for preparing the same, and more particularly, to a novel imidazole derivative showing fluorescence by excited-state intramolecular proton transfer (ESIPT) and a method for preparing the same.

Imidazole derivatives are one of the most important nitrogen-containing heterocycle organic compounds because they are rich in natural products and pharmacologically active compounds, and so far have been extensively studied in various applications such as biomimetic materials, drugs and composite materials for organic solar cells. It has been.

In particular, studies have recently been reported that tetrasubstituted tetrasubstituted imidazole derivatives can be used as fluorescent light emitting materials for organic light emitting diodes (OLEDs) or laser materials.

 Alicia Reyes-Arellano, Omar Gomez-Garc ㅽ a, Jenifer Torres-Jaramillo, Synthesis of azolines and imidazoles and their use in drug design, Med. Chem. (Los Angeles) 6 (2016) 561-570.  Pedro Molina, Alberto Tarraga, Francisco Oton, Imidazole derivatives: a comprehensive survey of their recognition properties, Org, Biomol. Chem. 10 (2012) 1711-1724.  J.C. Lee, J.T. Laydon, P.C. McDonnell, T.T. Gallagher, S. Kumar, D. Green, D. McKulty, M. Blumenthal, J.R. Heys, S.W. Landvatter, J.E. Strikler, M.M. McLaughlin, I.R. Seimen, S.M. Fisher, G.P. Livi, J.R. White, J.L. Adams, P.R. Young, A protein kinase involved in the regulation of inflammatory cytokine biosynthesis, Nature 372 (1994) 739-746.  Q. Zhang, J. Li, K. Shizu, S. Huang, S. Hirata, H. Miyazaki, C. Adachi, Design of efficient thermally activated delayed fluorescence materials for pure blue organic light emitting diodes, Am. Chem. Soc. 134 (2012) 14706-14709.  S. Park, O. Kwon, S. Kim, S. Park, M.G. Choi, M. Cha, S.Y. Park, D.J. Jang, Imidazole-based excited-state intramolecular proton-transfer materials: synthesis and amplified spontaneous emission from a large single crystal, J. Am. Chem. Soc. 127 (2005) 10070-10074.

The present invention aims to provide a novel imidazole derivative that can be applied to organic light emitting devices, fluorescent sensors, organic lasers, etc. by exhibiting exciton-state intermolecular proton transfer (ESIPT) and exhibiting strong fluorescence without self-absorption. do.

In order to achieve the object as described above, the present invention proposes an imidazole derivative represented by the following Chemical Formula 1 and having an excited state intermolecular proton transfer (ESIPT) property:

[Formula 1]

(In the above formula, X is halogen).

In addition, an imidazole derivative represented by the following Chemical Formula 2 is proposed:

[Formula 2]

.

.

In addition, an imidazole derivative represented by the following Chemical Formula 3 is proposed:

[Formula 3]

.

.

In addition, an imidazole derivative represented by the following Chemical Formula 4 is proposed:

[Formula 4]

.

.

In addition, the present invention is a method for producing an imidazole derivative having the ESIPT characteristics, in a solution containing salicylaldehyde and halogenated aniline, α-diketone and ammonium acetate ( ammonium acetate) is added and reacted to produce an imidazole derivative represented by Formula 5 below, and a method for preparing an imidazole derivative through a one-pot multicomponent reaction is proposed:

[Formula 5]

(In the above formula, X is halogen).

In addition, the halogenated aniline is 4-chloroaniline (4-chloroaniline) or 4-bromoaniline (bromoaniline) proposes a method for producing an imidazole derivative having the ESIPT characteristic, characterized in that.

In addition, the present invention proposes an imidazole derivative represented by the following formula (6) and having exciton-to-molecular proton transfer (ESIPT) properties as another imidazole derivative for achieving the object of the above-mentioned invention:

[Formula 6]

(In the above formula,

X is halogen and R1 and R2 are each independently substituted aryl).

In addition, an imidazole derivative represented by the following formula 7 is proposed:

[Formula 7]

.

.

In addition, an imidazole derivative represented by the following formula (8) is proposed:

[Formula 8]

.

.

In addition, an imidazole derivative represented by the following formula (9) is proposed:

[Formula 9]

.

.

In addition, the present invention is a method for producing an imidazole derivative having the ESIPT characteristic, in a solution containing salicylaldehyde and halogenated aniline, benzyl acetate and ammonium acetate are used. A method of preparing an imidazole derivative through a one-pot multicomponent reaction is proposed, comprising adding and reacting to prepare an imidazole derivative represented by the following Chemical Formula 10:

[Formula 10]

(In the above formula, X is halogen).

In addition, the halogenated aniline is 4-chloroaniline (4-chloroaniline) or 4-bromoaniline (bromoaniline) proposes a method for producing an imidazole derivative having the ESIPT characteristic, characterized in that.

Furthermore, the present invention, in another aspect of the invention, proposes a laser device and an organic electroluminescent device comprising an imidazole derivative having the ESIPT properties.

In the imidazole derivatives according to the present invention, the acenaphtho [1,2-d] imidazole ring effectively extends the conjugate length, and the introduced halogen atoms are bathochromically shifted by improving the charge transfer properties. ) It exhibits strong ESIPT fluorescence in orange color, and another imidazole derivative according to the present invention has a structure in which electron accepting substituents such as halogen atoms are introduced into the proton donor, so that the fluorescence properties are greatly improved and strong without severe self-absorption Since it exhibits blue light emission and has four phenyl groups introduced into the central imidazole ring, the interaction between molecules between the adjacent molecules is limited and shows strong fluorescence not only in solution but also in a solid state. Useful for light-emitting elements, chemical sensors, solar energy concentrators, UV stabilizers, etc. Can be used.

In addition, the method for producing an imidazole derivative having ESIPT characteristics according to the present invention is capable of synthesizing an imidazole derivative having excellent fluorescence characteristics through a one-pot multicomponent reaction method with a high yield of up to 70%. You can.

1 is a view showing a process of synthesizing AHPI-F, AHPI-Cl and AHPI-Br through a one-pot multicomponent reaction in Example 1 of the present application.
2 (a) to 2 (c) are a diagram of an Oak Ridge Thermal Ellipsoid Plot (ORTEP) of AHPI-F, AHPI-Cl and AHPI-Br, respectively.
3 (a) to 3 (c) are absorption spectra and emission spectra of AHPI-F, AHPI-Cl and AHPI-Br, respectively.
4 is a diagram showing the molecular orbital distribution of substances in HOMO and LUMO states of AHPI-F, AHPI-Cl and AHPI-Br using the DFT / B3LYP method.
5 (a) and 5 (b) are TGA and DSC curves for AHPI-F, AHPI-Cl and AHPI-Br, respectively.
6 is a view showing a process of synthesizing BHPI-Cl and BHPI-Br through a one-container multi-component reaction in Example 2 of the present application.
7 (a) and 7 (b) are OAK Ridge Thermal Ellipsoid Plots (ORTEPs) of BHPI-Cl and BHPI-Br, respectively.
8 (a) and 8 (b) are schematic diagrams of intermolecular hydrogen bond crystal filling of BHPI-Cl and BHPI-Br, respectively.
9 (a) and 9 (b) are FT-IR spectra of BHPI-Cl and BHPI-Br, respectively, and FIGS. 9 (c) and 9 (d) are Raman spectra of BHPI-Cl and BHPI-Br, respectively. to be.
10 (a) and 10 (b) are UV-Vis absorption spectrum and PL spectrum of BHPI-Cl, respectively, and FIGS. 10 (c) and 10 (d) are UV-Vis absorption spectrum of BHPI-Br, respectively. PL spectrum.
Figure 11 shows the boundary molecular trajectories (HOMO and LUMO) of BHPI-Cl and BHPI-Br calculated by TD-DFT, B3LYP / (6-31G (d, p) basal set.
12 (a) and 12 (b) are a diagram of the distribution of the millic atomic charges for BHPI-Cl and BHPI-Br, respectively.
13 (a) and 13 (b) are the molecular electrostatic potential (MEP) total density diagram (left), electrostatic potential diagram (center) and contour density diagram (right) for BHPI-Cl and BHPI-Br, respectively.
14 (a) and 14 (b) are TGA curves (red) and DSC curves (blue) for BHPI-Cl and BHPI-Br, respectively.

In the description of the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

The embodiments according to the concept of the present invention may be modified in various ways and have various forms, and thus, specific embodiments will be illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiment according to the concept of the present invention to a specific disclosure form, and it should be understood to include all modifications, equivalents, or substitutes included in the spirit and scope of the present invention.

The terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “include” or “have” are intended to indicate that a feature, number, step, action, component, part, or combination thereof described is present, and one or more other features or numbers. It should be understood that it does not preclude the presence or addition possibilities of, steps, actions, components, parts or combinations thereof.

And, unless specified otherwise, the following terms and phrases used herein have the following meaning.

"Aryl" means an aromatic hydrocarbon radical derived from the removal of one hydrogen atom from a single carbon atom of the parent aromatic ring system. For example, an aryl group can have 6 to 20 carbon atoms, 6 to 14 carbon atoms, or 6 to 12 carbon atoms. Typical aryl groups include, but are not limited to, radicals derived from benzene (eg, phenyl), substituted benzene, naphthalene, anthracene, biphenyl, and the like.

The term "substituted" with respect to the aryl refers to aryl in which one or more hydrogen atoms are each independently substituted with a non-hydrogen substituent. Typical substituents include ^{-X, -R, -O -, =} O, -OR, -SR, -S -, -NR 2, -N + R 3, = NR, -CX 3, -CN, -OCN, - SCN, -N = C = O, -NCS, -NO, -NO ₂ , = N ₂ , -N ₃ , -NHC (= O) R, -C (= O) R, -C (= O) NRR ^{_{-S (= O) 2 O -}} , -S (= O) 2 OH, -S (= O) 2 R, -OS (= O) 2 OR, -S (= O) 2 NR, -S (= O) R, -OP (= O) (OR) ₂ , -N (= O) (OR) 2, -N (= O) (O -) 2, -N (= O) (OH) 2, -N (O) (OR) (O -), -C ( = O) R, -C (= O) X, -C (S) R, -C (O) OR, -C (O) O -, -C (O) O -, -C (O) SR, -C (S) SR, -C (O) NRR, -C (S) NRR, -C (= NR) NRR, where each X is independently halogen: F, Cl, Br, or I, and R is Independently H, alkyl, aryl, arylalkyl, heterocycle, or protecting group or prodrug moiety).

Hereinafter, examples will be described in detail to specifically describe the present specification.

However, the embodiments according to the present specification may be modified in various other forms, and the scope of the present specification is not interpreted to be limited to the embodiments described below. The embodiments of the present specification are provided to more fully describe the present specification to those skilled in the art.

<Example 1> Synthesis of AHPI-F, AHPI-Cl and AHPI-Br

As shown in Fig. 1, α-diketone (a-diketone) was added to a solution of aromatic aldehyde (2) (1.0 eq) and aromatic amine (3) (1.0 eq) in glacial acetic acid. 1) After adding (1 eq) and ammonium acetate (1.5 eq), the mixture was refluxed at 120 ° C for 12 hours. After the reaction was completed, a large amount of water was poured, the pH was neutralized, the dark precipitate was filtered, and the product was purified by silica gel column chromatography using hexane-ethylacetate (0-10%) as an eluent, and ethyl Crystallized from ethyl acetate to obtain orange crystals of AHPI-F, AHPI-Cl and AHPI-Br as shown below (yield: 57-63%).

(1) 2- (7- (4-fluorophenyl) -7H-acenaphtho [1,2-d] imidazol-8-yl) phenol (AHPI-F)

¹ H NMR (300 MHz, chloroform-d) d 12.79 (s, 1H), 7.85 (d, J = 6.9 Hz, 1H), 7.68 (dd, J = 8.3, 6.4 Hz, 2H), 7.59-7.47 (m , 3H), 7.38-7.24 (m, 3H), 7.22-7.04 (m, 2H), 6.98 (d, J = 6.9 Hz, 1H), 6.75 (dd, J = 8.1, 1.6 Hz, 1H), 6.60- 6.48 (m, 1 H). ¹³ C NMR (300 MHz, chloroform-d) d 158.10 (s), 148.68 (s), 144.98 (s), 138.28 (s), 134.44 (s), 131.72 (s), 130.22 (s), 129.66 (s) ), 128.70 (d, J = 8.7 Hz), 128.07 (s), 127.64 (s), 127.16 (s), 126.42 (s), 125.79 (s), 121.43 (s), 119.19 (s), 118.33 (s) ), 118.06 (s), 117.78 (s), 117.48 (s), 113.66 (s). High-resolution MS (HR-FAB ㆎ): m / z found for C ₂₅ H ₁₅ FN ₂ O [M ㆎ H] ㆎ: 379.CHN: C: 79.3584, H: 4.1151, N: 7.4210. MP = 208-210 ° C.

(2) 2- (7- (4-chlorophenyl) -7H-acenaphtho [1,2-d] imidazol-8-yl) phenol (AHPI-Cl)

¹ H NMR (300 MHz, chloroform-d) d 12.70 (s, 1H), 7.88 (d, J = 6.8 Hz, 1H), 7.72 (dd, J = 8.2, 6.5 Hz, 2H), 7.66-7.47 (m , 5H), 7.35 (dd, J = 8.3, 7.0 Hz, 1H), 7.18 (ddd, J = 8.6, 7.0, 1.6 Hz, 1H), 7.13-7.00 (m, 2H), 6.79 (dd, J = 8.1 , 1.6 Hz, 1H), 6.63-6.51 (m, 1H). ¹³ C NMR (300 MHz, chloroform-d) d 158.08 (s), 148.62 (s), 136.99 (s), 135.73 (s), 130.84 (s), 130.32 (s), 129.70 (s), 128.15 (d) , J = 4.6 Hz), 127.74 (s), 127.21 (s), 126.40 (s), 125.95 (s), 121.53 (s), 119.30 (s), 118.42 (s), 118.11 (s). High-resolution MS (HR-FAB ㆎ): m / z found for C ₂₅ H ₁₅ ClN ₂ O [M ㆎ H] ㆎ: 395.CHN: C: 76.1480, H: 3.9217, N: 7.0767.MP = 195- 199 ℃.

(3) 2- (7- (4-bromophenyl) -7H-acenaphtho [1,2-d] imidazol-8-yl) phenol (AHPI-Br)

¹ H NMR (300 MHz, chloroform-d) d 12.68 (s, 1H), 7.88 (d, J = 6.8 Hz, 1H), 7.73 (dd, J = 17.1, 7.8 Hz, 4H), 7.61-7.52 (m , 1H), 7.45 (d, J = 8.6 Hz, 2H), 7.40-7.29 (m, 1H), 7.18 (t, J = 7.7 Hz, 1H), 7.07 (dd, J = 12.1, 7.6 Hz, 2H) , 6.79 (d, J = 7.1 Hz, 1H), 6.57 (t, J = 7.1 Hz, 1H). ¹³ C NMR (300 MHz, chloroform-d) d 158.06 (s), 148.56 (s), 137.51 (s), 133.82 (s), 130.33 (s), 129.65 (d, J = 8.0 Hz), 128.45 (s ), 128.11 (s), 127.74 (s), 127.21 (s), 126.38 (s), 125.98 (s), 123.69 (s), 121.53 (s), 119.32 (s), 118.44 (s), 118.11 (s) ), 113.58 (s). High-resolution MS (HR-FAB ㆎ): m / z found for C ₂₅ H ₁₅ BrN ₂ O [M ㆎ H] ㆎ: 440. CHN: C: 68.2480, H: 3.3396, N: 6.4046. MP 203-212 ° C.

The ORTEP plots of AHPI-F, AHPI-Cl and AHPI-Br are depicted in Figure 2 and the structure refinements are summarized in Table 1 below. The compounds correspond to the monoclinic space group P2 _{1 / C} , AHPI-F is a = 8.3355 Å, b = 22.8736 Å, c = 9.4113 Å, AHPI-Cl is a = 7.870 Å, b = 17.52 Å, c = 13.529 Å, AHPI- Br was found to have a cell size of a = 7.901 Å, b = 17.460 Å, c = 13.707 Å.

[Table 1] Crystal data and structure refinement for AHPI-F, AHPI-Cl and AHPI-Br

The binding length and binding angle of each compound are presented in Tables 2 and 3, respectively. Different halogens were located at the C19 position, showing a lattice structure with different crystal structures. The fused ring systems of acenaphtho groups (C-3 and C11) are coplanar with the imidazole ring, and the conjugate length is extended within each molecule. The halogen-attached phenyl moiety has dihedral angles of 120.34 (18), 119.2 (2) and 119.81 (18) at C17-C16-N1 for AHPI-F, AHPI-Cl and AHPI-Br respectively. Twisted out of the average plane of the acenaphthoimidazole ring, the phenyl ring at the N-1 position deviates from the planarity of the molecular backbone of the three compounds (see Figure 2). The phenyl moiety, which is bonded to C14 and substituted with a hydroxyl group, is almost coplanar with the imidazole ring. The torsion angle of C14-C22-C23-O29 is 3.7 3 for AHPI-F and 1.1 (3) for AHPI-Cl and AHPI-Br. The flatness of these compounds is probably due to the hydrogen bonding in the O29H / N13 molecule. The C18-C19 and Br28-C19 binding lengths are 1.734 (3) Å and 1.891 (2) 상대적, which are relatively identical and normal. The C-N bond of the imidazole ring has a range of 1.343 (3) Å (AHPI-F), 1.330 (3) Å (AHPI-Cl) and 1.329 (3) Å (AHPI-Br) to represent partial double bonds.

Table 2: Binding length for AHPI-F, AHPI-Cl and AHPI-Br

Table 3: Binding angles for AHPI-F, AHPI-Cl and AHPI-Br

3 (a) to 3 (c) are absorption and emission spectra of chloroform (CHCl ₃ ) acetonitrile (MeCN) and ethanol (EtOH) of AHPI-F, AHPI-Cl and AHPI-Br, respectively. The absorption spectra of molecules in chloroform and acetonitrile showed similar ground state properties. However, slightly different absorption spectra were observed in polar ethanol. That is, in ethanol, an absorption spectrum of about 15 nm was observed as compared to that of chloroform and acetonitrile, indicating a negative solvatochromism. The absorption maximum point (λ _{max, abs} ) near 325 nm may be due to an aryl ring, and an absorption band of 200 to 375 nm is assigned to π-π ^* electron transition of the acenaphtho [1,2-d] imidazole ring do.

In the luminescence spectrum, the compounds showed similar luminescence except for a slight hypochromic shift emission in ethanol. When S0 → S1 (π-π ^* ) excitation (λ _max = 324 nm), strong fluorescence at 575 nm and very weak shoulder-like luminescence were observed near 420 nm. The previously reported ESIPT molecule, 2- (1,4,5-triphenyl-1H-imidazol-2-yl) -phenol (HPI), exhibits blue fluorescence at 465 nm and a very weak shoulder-like luminescence at about 390 nm. AHPI-F, AHPI-Cl and AHPI-Br showed red shifted luminescence compared to the HPI molecule due to the extended conjugate length through acenaphtho [1,2-d] imidazole. The excitation spectrum observed in each band is the same, spectrally identical to the lowest absorption band, indicating that the two fluorescent bands are from the same ground-state species. Therefore, the 420nm band in the normal E ^* fluorescence, the 575nm band K ^* - may be any tautomeric (K * -tautomer) fluorescence undoubtedly. AHPI-Cl and AHPI-Br showed almost the same spectral behavior as AHPI-F. The optical band gap (E _g ) of all the above compounds can be estimated by the following equation (1) (Tauc's equation).

According to the experimental and theoretical values of λ _max and E _g of the frontier molecular orbital and Tauc approach by time-dependent density functional theory (TD-DFT) calculations, the experimental values for the compound molecules are in accordance with the theoretical expected values. It was found to be a good match.

The optimized structure of all molecules was calculated using Gaussian 09 with B3LYP / 6-31 (d, p) basis set, atomic millisecond charges and boundaries to examine the theoretical aspects of the experimentally observed results. Electronic properties were analyzed, including the frontier molecular orbital. 4 shows the molecular orbital distribution of materials in the HOMO and LUMO states. For each of AHPI-F, AHPI-Cl and AHPI-Br, the bandgap values calculated in the singlet state were 2.26, 2.93 and 2.83 eV, which was in good agreement with the experimental results. For AHPI-F, AHPI-Cl and AHPI-Br, trajectories on the imidazole ring are electronically close, or trajectories on the imidazole ring are electronically aligned along the direction of the N1-N3 axis for HOMO levels, or the N1-M3 axis It is noteworthy to form a right angle with (Fig. 4). The results of the experiment suggest that the electron push on the imidazole ring through the 2-carbon position effectively influenced the N-based donor donor strength, so HOMO 1 is preferred because it is aligned electronically in the same direction. This comes out. HOMO and LUMO of the substituted acenaphtho [1,2-d] imidazole showed π-symmetry. From HOMO and LUMO, the electron density distribution showed the transition from the phenol ring to the acenaphtho [1,2-d] imidazole moiety. Long wavelength absorption calculated for AHPI-F (ca. 548.77 nm, oscillator intensity (f) = 0.0313), long wavelength absorption calculated for AHPI-Cl (ca. 424.91 nm, oscillator intensity (f) = 0.0543) and AHPI- The long wavelength absorption (ca. 437.52 nm, oscillator intensity (f) = 0.0427) calculated for Br is a mixture of different transitions: HOMO → LUMO, HOMO → LUMO +1, HOMO → LUMO + 2, etc. The shape of the HOMO looks very similar between the molecules. However, LUMO + 1 and LUMO + 2 of AHPI-F, AHPI Cl and AHPI-Br are delocalized through an acceptor and fused π system. This change in electron density can act as a driving force for very fast intramolecular proton migration in these compounds when excited in a singlet excited state. Therefore, the phenolic ring has a smaller electron density in the excited state, which was the driving force for the proton transfer to the acenaph to [1,2-d] imidazole derivatives in the excited state. Therefore, the HOMO-to-LUMO transition can be attributed to π-π ^* excitation with internal charge transfer properties.

According to the calculation results of the M 컨 lliken atomic charge, as expected, N atoms are the most electronegative atomic sites in the molecule, and the calculated charge density at the N atoms ranges from -0.665 to -0.998. All H atoms from the phenyl ring are electropositive and range between 0.52 and 0.99. On the other hand, some carbon atoms except C22, C23, C14, C7, C10, C12, C13, and C19 all have a negative charge due to the π electron interaction. The H atom of O-H has a high positive charge, all carbon atoms of the imidazole ring have a positive charge, and C1 has the highest positive charge density. Compared to N13, N1 has more electronegative properties due to heavy elements (Cl and Br) parallel to the phenyl ring.

The results of TGA-DSC analysis performed in a nitrogen atmosphere and a temperature range of 30-700 ° C. for each molecule are shown in FIG. 5. All molecules showed good thermal stability and the decomposition temperature with 10% weight loss was measured at 389, 393 and 391 ° C. for AHPI-F, AHPI-Cl and AHPI-Br respectively. The melting points measured by the peaks of the DSC traces are 222, 210 and 223 ° C. for AHPI-F, AHPI-Cl and AHPI-Br, respectively. During the second heating, no melting point was observed even though sufficient time was allowed to cool in the atmosphere. Once it became an amorphous solid, it did not return to the crystalline state. According to the TGA / DSC curve of the compound, two endothermic peaks and one exothermic peak are observed. The TGA / DSC spectrum of the compound showed the decomposition curve of a typical organic compound.

<Example 2> Synthesis of BHPI-Cl and BHPI-Br

6, salicylaldehyde (1) (1.0 eq) and halogenated aniline (4-chloroaniline or 4-bromoaniline) in 20 mL acetic acid (2) (1.0 eq.) To the magnetically stirred solution, benzyl (3) (1.0 eq.) And ammonium acetate (1.5 eq.) Were added at room temperature, and then the reaction mixture was kept at 120 ° C for 12 hours. Refluxed. After completion of the reaction, the solution was quenched with a large amount of water, and the pH was neutralized with sodium bicarbonate. The precipitate was then filtered and washed with water. The obtained product was purified by silica gel column chromatography using hexane-ethylacetate (9: 1) as the eluent, and single crystals of BHPI-Cl and BHPI-Br were obtained from the ethyl acetate solution as follows. Obtained (Yield: 68-70%).

(1) 2- (1- (4-Chlorophenyl) -4,5-Diphenyl-1H-Imidazol-2-yl) Phenol (BHPI-Cl)

¹ H NMR (300 MHz, CDCl ₃ ): δ 13.28 (s, 1H), 7.52 (dd, J = 7.8, 1.9 Hz, 2H), 7.38-7.03 (m, 14H), 6.54 (td, J = 9.1, 8.6, 4.3 Hz, 2H). ¹³ C NMR (300 MHz, CDCl ₃ ) δ 158.60 (s), 145.07 (s), 136.41 (s), 135.73 (s), 133.06 (s), 131.51 (s), 130.39 (t, J = 3.7 Hz) , 129.73 (s), 128.89 (s), 128.51 (s), 127.34 (s), 127.10 (s), 126.18 (s), 123.41 (s), 118.26 (s), 118.02 (s), 112.92 (s) . MP: 201-203 ° C. Elemental analysis calcd. for C ₂₇ H ₁₉ ClN ₂ O: C, 76.68; H, 4.53; Cl, 8.38; N, 6.62. O, 3.78. Found C, 76.5001; H, 4.6113; N, 6.7546.

(2) 2- (1- (4-Chlorophenyl) -4,5-Diphenyl-1H-Imidazol-2-yl) Phenol (BHPI-Br)

¹ H NMR (300 MHz, CDCl ₃ ): δ 13.45-13.04 (m, 1H), 7.55-7.43 (m, 4H), 7.35-7.18 (m, 6H), 7.17-6.96 (m, 6H), 6.64- 6.40 (m, 2H). ¹³ C NMR (300 MHz, CDCl ₃ ) δ 158.60 (s), 145.11 (s), 135.89 (s), 135.68 (s), 135.34 (s), 131.51 (s), 130.50 (s), 130.33 (s) , 130.08 (d, J = 2.7 Hz), 129.75 (s), 128.87 (s), 128.50 (s), 127.33 (s), 127.09 (s), 126.15 (s), 118.24 (s), 118.01 (s) , 112.93 (s). MP: 217-222 ° C. Elemental analysis calcd. for C ₂₇ H ₁₉ BrN ₂ O: C, 69.39; H, 4.10; Br, 17.10; N, 5.99. O, 3.42. Found C, 69.3942; H, 4.2815; N, 6.0235.

7 is an ORTEP (Oak Ridge Thermal Ellipsoid Plot) of BHPI-Cl and BHPI-Br molecules. In molecular design, four phenyl groups were intentionally bound to the central imidazole unit to coordinate the intermolecular interaction, taking into account that the molecular packing mode strongly influences the properties of the compound. Synthesized molecules combine chromophores with steric groups, limiting excessively tight stacking and consequent intermolecular vibronic relaxation, enhancing luminescence properties, resulting in intense sky blue in solution as well as in solid state It shows fluorescence. These structural properties of the BHPI-Cl and BHPI-Br molecules were well revealed by X-ray crystallographic analysis (see Table 4 below). The tetraphenyl substituted imidazole derivative synthesized in this example was crystallized into an orthorhombic crystal structure having a space group P2 ₁ 2 ₁ 2 ₁ .

[Table 4] Crystal data and structure refinement for BHPI-Cl and BHPI-Br

According to the bond distances and band angles listed in Table 5 below, the atoms of N1, N16, C2, C9, and C17 in both molecules form five rigid constituent rings, and the average deviation of all atoms is 0.02636 in both rings. It was Å. All C = C and C = N bond distances of the two molecule 5-membered heterocycle ring were identical and typical for the imidazole ring. The main difference between the BHPI-Cl and BHPI-Br compounds is the binding distance between C21-Cl30 and C21-Br30, which was confirmed to be 1.734 1. and 1.896Å, respectively. C2-C3-C8-H8 (-2.4 °), N1-C18-C19-H19 (-1.6 °), C9-C10-C15-H15 (-2.6 °) and C17-C24-C29-H29 (0.2 °) The different torsion values of (see Table 6 below) indicate that the phenyl ring of C17 is C25-O31-H29. It shows that the -OH group in N16 has a planar conformation due to the intramolecular hydrogen bonding. Also, C-H… O, C-H… π, C-C… Weak, intermolecular interactions, including H, CCCH interactions, helped to lock molecular rotation and increase the stability of the molecule (Fig. 8. (x, -x + 1/2, -x, x + 1 / 2 symmetrical position)). Consequently, the suppressed non-radiative pathway of the excited state can increase the photoluminescence efficiency of the molecule. The experimental and calculated binding lengths and angles for BHPI-Cl and BHPI-Br are single crystals of the molecular form obtained from density functional theory (DFT) calculations for the remarkably twisted molecular forms at the 1- and 5-positions of the central imidazole. It showed good agreement with the experimental results from.

Table 5: Experimental and calculated binding lengths and angles for BHPI-Cl and BHPI-Br

^a DFT-B3LYP 6-31G (d, p) optimized geometric parameters from the base set

Table 6: Torsional values for BHPI-Cl and BHPI-Br

The experimental infrared spectra of BHPI-Cl and BHPI-Br are as shown in Figs. 9 (a) and 9 (b), and the band assignments are described in Table 7 below. The FT-IR spectrum of phenolic OH (phenolic OH) shows weak bands due to stretching vibrations of OH groups at 3065 cm ^-1 and 3054 cm ^-1 . The weak absorption bands of 1961-1900 cm ^-1 and 1956-1901 cm ^-1 are characteristic CH aromatic overtone bending vibrations of BHPI-Cl and BHPI-Br, respectively. The absorption bands at 1490 cm ⁻¹ and 1486 cm ⁻¹ are due to C = N elongation vibration. The absorption bands at 1392 cm ^-1 and 1388 cm ^-1 are due to the stretching vibrations of the CO bands present in the phenol ring. Aromatic CC occurs in bands of 1589 cm ^-1 and 1590 cm ^-1 . CN elongation vibration is present at 1256 cm ^-1 . On the other hand, for BHPI-Cl and BHPI-Br, the bending vibration of the HCC band is 1135 cm ^-1 and 1147 cm ^-1 , the twisting angle of the CCCC bending vibration is 720 cm ^-1 and 721 cm ^-1 , and the twisting of the HCCC bending vibration The angle is at 780 cm ^-1 and 787 cm ^-1 . The C-Br and C-Cl extension bands were assigned to 699 cm ^-1 and 697 cm ^-1 , respectively.

[Table 7] Experimental vibration frequencies of BHPI-Cl and BHPI-Br (IR and Raman)

The observed FT-Raman spectra of BHPI-Cl and BHPI-Br are shown in FIGS. 9 (c) and 9 (d). The observed frequency of vibrations and the corresponding vibration allocation and intensity are listed in Table 7. Most of the bands of the Raman spectrum are related to the IR spectrum. The bands of 1034cm ^-1 and 1033cm ^-1 are related to weak CH bending frequencies. The vibration extension frequency of the CN band was observed at 1240 cm ^-1 . An important CN band for imidazole is detected in a band of 1240 cm ^-1 . The frequencies of 750 cm ^-1 and 730 cm ^-1 are due to the C-Cl and C-Br bands of BHPI-Cl and BHPIBr, respectively. At 1559 cm ^-1 and 1555 cm ^-1 a strong elongation frequency of the C = N band was observed. The bands of HCC, HCCC and CCCC observed in the IR spectrum were not monitored in the Raman spectrum.

To examine the photophysical properties of BHPI-Cl and BHPI-Br, UV-vis absorption and photoluminescence (PL) measurements were performed using three different solvents at room temperature. A polar protic solvent (ethanol (EtOH)), a polar aprotic solvent (acetonitrile (MeCN)) and a non-polar aprotic solvent (chloroform (CHCl ₃ )) were selected and the concentration of each solution was maintained at 10 μM. As shown in Figure 10, the absorption spectrum showed two major absorption bands at about 285 nm and 318 nm. The first band around 285nm is due to the π-π ^* transition of the C = N group, and the second band around 318nm is derived from intramolecular hydrogen bonding between OH and N of each molecule. In polar aprotic magnetic solvents such as acetonitrile, the band of 318 nm shifted to a longer wavelength (bathochromic shift) because both molecules stabilized in their respective excited states. This band shifted toward a short wavelength in a polar protic solvent (hypsochromic shift), indicating that both molecules were stabilized to the ground state. Thus, BHPI-Cl and BHPI-Br act as both Lewis acids and Brønsted bases due to their specific interactions with protic and aprotic solvents, respectively.

The observed PL emission spectra of BHPI-Cl and BHPI-Br in different solvents in the wavelength region of 250-700 nm showed that there was no correlation between the absorption spectrum and the mirror image, and the excited state compared to the ground state (S ₀ ) S ₁ ) confirms the geometric rearrangement of the two molecules (FIG. 10). As a result of ESIPT, large Stokes' shift values were obtained for both molecules. Under excitation at 318 nm, BHPI-Cl and BHPI-Br show dual dual emission, showing that both the enol (E ^* ) and keto (K ^* ) forms are in the excited state. The excitation spectrum monitored in each band is the same, spectrally identical to the lowest absorption band, indicating that the two fluorescent bands are from the same ground-state species and ground-state species. Thus the 380nm band in the normal E ^* fluorescence, the 480nm band K ^* - You can specify a call variant (K ^* -tautomer) fluorescent without a doubt. The optical band gap (E _g ) of the two compounds can be estimated by the equation (1) (Tauc's equation).

According to experimental and theoretical values of λ _max and E _g of frontier molecular orbital and Tauc approach by time-dependent density functional theory (TD-DFT) calculation, experimental values for BHPI-Cl and BHPI-Br molecules Was found to agree well with the theoretical expected value.

The density functional theory (DFT) method has been very popular over the past decades due to its accuracy and shorter calculations. There is no doubt that recent advances in DFT computation provide very useful information for understanding molecular properties and explaining the behavior of atoms in a molecule. The boundary molecular orbital gap helps to characterize the chemistry of the molecule as well as its chemical reactivity. For example, molecules with small boundary molecular orbital gaps are more polarized and are generally associated with high chemical reactivity. The molecular optimization and quantum chemical calculations of BHPI-Cl and BHPI-Br were performed by DFT calculation using B3LYP / (6-31G (d, p) basis set). The optimized ground state geometry along with the relevant molecular orbital plots of HOMO and LUMO for is shown in Figure 11. HOMO appears non-localized in the entire molecule, and electron density is spread across the imidazole-phenyl units. In addition, the energy gap (3.38eV) between HOMO and LUMO of BHPI-Cl is relatively similar to BHPI-Br (3.38eV) and matches well with the actual absorption spectrum. It was measured in three different solutions of and shows two blue emission peaks at 385 and 480 nm due to π-π ^* and n-π ^* transitions, respectively.

TD-DFT calculations were also performed using the B3LYP / 6-31 G (d, p) basal set. From the calculation results of HOMO and LUMO, the electron density distribution showed electron transfer from the imidazole moiety to the 4-bromobenzene or 4-chlorobenzene ring. The long wavelength absorption calculated for BHPI-Cl (ca. 360.61 nm, oscillator intensity (f) = 0.2994) and the long wavelength absorption calculated for BHPI-Br (ca. 367.25 nm, oscillator intensity (f) = 0.3001) are different. The transition is a mixture of HOMO → LUMO, HOMO → LUMO +1, HOMO → LUMO + 2, etc. The shape of the HOMO looks quite different for the two molecules due to the heavy atomic effect. This change in electron density can act as a driving force for very fast intramolecular proton migration in these compounds when excited to the S ₁ state.

The calculation of millisecond atomic charges is important because atomic charges can affect dipole moments, polarizability and the electronic structure of molecules. The calculated millisecond charge is described in FIG. 12 and the calculated atomic charge list is shown in Table 8 below.

The O and N atoms are the most negatively charged in each molecule, the calculated charge density of the O atom is -0.783 and the N atom is in the range of -0.975 to -1.069. All H- atoms are electropositive, and O-H protons are more electropositive than aromatic protons due to the intramolecular hydrogen bonding. On the other hand, only some of the carbon atoms are positively charged, and the rest are negatively charged. Carbon atoms except C2, C9, C17, C18 and C25 are electrically negative. All carbon atoms in the imidazole ring are positively charged, and C2 atoms have the highest positively charged density.

Table 8: Millic atom atomic charges of BHPI-Cl and BHPI-Br calculated at B3LYP / 6-31 G (d, p)

^a Atomic numbering corresponds to the description in FIG. 7

Molecular Electrostatic Potential (MEP) was used to examine the chemical reactivity of the molecule. The surfaces of BHPI-Cl and BHPI-Br were plotted for an optimized electrostatic structure using B3LYP / 6-31G (d, p). MEP is very useful for predicting the molecular reaction behavior, and is a good guideline for evaluating molecular reactivity for positively or negatively charged reactants as well as hydrogen bond interactions. 13 shows the MEP total density diagram, the electrostatic potential (ESP) diagram and the contour density diagram of the two compounds. The MEP map of the two molecules shows that the oxygen of the C9 atom and the bonded phenyl ring are the most negative regions. The hydrogen atom has a maximum region of positive charge. Most green areas on the MEP surface fall in the middle of the potential between red and blue. The MEP map is an intermolecular interaction in which molecules are connected by a supramolecular chain along the b-axis direction, C27-H27… It is supported by O31 [symmetry code x, -x + 1/2, -x, x + 1/2] (Fig. 3).

The thermal properties of BHPI-Cl and BHPI-Br were evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC is used to determine the glass transition temperature (T _g ) of a material at a heating rate of 10 ° C./min under nitrogen. No crystallization exothermic peak and melting endothermic peak were observed in the range of 28 to 700 ° C. The DSC / TGA curves of the compounds BHPI-Cl and BHPI-Br are shown in Figure 14. Compound BHPI-Cl showed high thermal stability up to 422 ° C. According to the TGA results, two endothermic peaks were observed at 206 ° C and 422 ° C, and no exothermic peak was observed. The first step of decomposition in the temperature range of 420 to 440 ° C was found to be 97-98% weight reduction. The final residue disappeared completely at 650 to 660 ° C. with exothermic reaction. Similarly, the DSC and TGA curves of compound BHPI-Br showed two peaks at 210 and 420 ° C, and the compound showed high thermal stability up to 425 ° C.

Claims (8)

Imidazole derivatives represented by the following formula 1 and having exciton-state intermolecular proton transfer (ESIPT) properties:
[Formula 1]

(In the above formula, X is halogen). According to claim 1,
The imidazole derivative represented by the following formula (2):
[Formula 2]

. According to claim 1,
The imidazole derivative represented by the following formula (3):
[Formula 3]

. According to claim 1,
Imidazole derivatives represented by the following formula (4):
[Formula 4]

. To a solution containing salicylaldehyde and halogenated aniline, α-diketone and ammonium acetate are added and reacted to obtain an imidazole derivative represented by Chemical Formula 5 below. Comprising the steps of manufacturing,
Method for preparing an imidazole derivative through a one-pot multicomponent reaction method:
[Formula 5]

(In the above formula, X is halogen). The method of claim 5,
The halogenated aniline is a method for producing an imidazole derivative characterized in that it is 4-chloroaniline (4-chloroaniline) or 4-bromoaniline (bromoaniline). A laser device comprising the imidazole derivative of claim 1. An organic electroluminescent device comprising the imidazole derivative of any one of claims 1 to 4.

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