Quantum chemical calculations of a novel Specie – Boron Nano Bucket (B16) and the interaction of its complex (B15-Li) with drug Resorcinol

Abstract

At Nano-scale level, innovative biomedical techniques are developed in advanced drug delivery systems and targeted Nano-therapy. Ultrathin needles provide a low invasive and highly selective means for molecular delivery and cell manipulation. This article studies the geometry and the stability of Boron Nano-Bucket (B16 Cluster of Bucket Shape) and B15-Li complex by using computational modeling methods. The equilibrium geometry of Boron Nano-Bucket and BNB-Li complex in the ground state have been determined and analyzed by Density functional theory (DFT) employing 6-311 G (d, p) as the basis set. The frontier orbital HOMO-LUMO gap, Chemical Softness, Chemical Hardness have also been calculated to understand its complete Chemical Properties. In this study, we have also performed BNB-Li complex interaction with drug Resorcinol. The binding character interactive species have been determined by NBO and AIM analysis. From these studies, we can say that BNB and BNB-Li complex may also potentially able to stabilize ions around their structure like Carbon Nano Niddle (CNN) in future. The polar characteristics of CNN and their ability to carry ionic species, Li doped Boron Nano-Bucket might be suitable to act as drug carrier through nonpolar biologic media.

Keywords

CNN HOMO-LUMO DFT BNB

1. Introduction

Special attention is paid to the biomedical and biotechnology applications of nanotechnology to nano medicine [1] and in particular to medical diagnostics and imaging [2], and to nano neurosurgery [3]. Innovative techniques operational at the nano scale level are being developed in therapeutic modalities, including advanced selective drug delivery systems and targeted nano therapy [4]. In this context, ultrathin needles [5] provide a low invasive means for molecular delivery, manipulating cells, and transferring genes in living cells by using atomic force microscopes [6]. Some studies have recently demonstrated that chemically modified carbon nanotubes can act as nano needles easily crossing biological barriers and penetrating a variety of cell types [7, 8, 9]. This finding opens the potential of functionalized carbon nanotubes as a new form of direct drug delivery [10]. During the last decade many researchers focused on a systematic search for new materials mainly consisting of pure or mixed boron, carbon, nitrogen, boron-hydrogen and metal-boron types of systems [11, 12]. Though some variety of possible structures in nanostructured materials like quasi-crystals [13], nanowires [14], nano ribbons [15], was identified, many forms however remain to be discovered. The existence of quasi-planar [16] and tubular [17] boron clusters was predicted theoretically and confirmed more recently experimentally [18, 19]. In addition, double-walled boron nanotubes were predicted to be highly stable [20].

In this paper, we are reporting a comparative study of the structure and quantum chemical calculations of Boron Cluster (B16) and Li doped Boron Cluster (B15-Li) which looks like a bucket so I named it Boran Nano bucket. Novel spherical boron clusters and structural transition from 2D quasi-planar structures to 3D double-rings are reported by Saikat Mukhopadhyay et al. [21] but the structure of B16 and B15-Li is totally different from thier design. To know its application in drug delivery as a carrier, binding strength and characteristics of system [B15-Li with Resorcinol] have been determined with the help of AIM analysis at BCP point. To the best of our knowledge bucket type structure of boron and BNB-Li complex interaction with drug Resorcinol and their detailed Density Functional Study with AIM analysis have not reported so far in the literature.

1.1 Computational details

The quantum chemical calculations were performed on Boran Nano bucket (B16 and B15-Li) using the Gaussian 09 code [22]. All calculations were carried out by solving the Kohn-Sham equations in the framework of the density functional theory (DFT) and 6-311 G (d, p) as the basis set [23]. The gradient corrected DFT with the three-parameter hybrid functional (B3) [24] for the exchange part and the Lee-Yang-Parr (LYP) [25] correlation function has been employed. It is worth mentioning here that B3LYP [26] has been successfully employed in several theoretical studies on atomic clusters [27, 28]. NBO analysis of B16 and B15-Li are calculated by NBO 4.0 program package [29]. Molecular interaction study of B15-Li with Resorcinol have been done with the help of AIMALL software [30].

2. Results and discussion

2.1 Optimized equilibrium parameters

Basically we have started work on Boron clusters doped with transition metals but during this study we have found interesting structure of B16 in Bucket Form. We have also designed Li doped B15 complex (to enhance its bonding character) by endohedral doping. This B16 and Li doped B15 Bucket type structures are found to be stable (as they have no imaginary frequency in vibrational analysis). The schematic representation of boron nano bucket considered in this study for the geometry optimization has been listed in Fig. 1. Table 1 collects the range of B-B bond distances and angles in B16 and Li doped B15 bucket type structures. The values of bond lengths are in the range from 1.56 to 2.42A ${}^{0}$ while the bond angles are from 55.01 to 134.11 degree. After endohedral doping of Li in BNB, the basic structure slightly stretched and become more unsymmetrical. This stretching in Li-B is due to the lone pair of B electron and Li electron repulsion. The calculated bond length of Li-B lays at 2.16A ${}^{0}$ in BNB-Li complex. The calculated bond length of B-B of non-interactive site in hexane ring is 1.66A ${}^{0}$ however B-B bond length of B-Li interaction site lays at 1.81A ${}^{0}$ . In BNB-Li bond length in between B-B lies in between 1.55A ${}^{0}$ –1.83A ${}^{0}$ .

Table 1
Bond length and Bond angles of Boron Nano bucket and Li doped BNB by (B3LYP)/6-311 G (d, p) methods

	Parameter	Range value [(B3LYP)/6-31G (d)]
BNB	Bond length (angstrom)	1.56–2.42
	Bond angles (degree)	55.01–134.11
BNB-Li	Bond length (angstrom)	1.82–1.56 (B-B) 2.16 (B-Li)
	Bond angles (degree)	73.88–174.94

Figure 1.

Model molecular structures of Boron Nano Bucket (B16), B15-Li, Resorcinol and B15-Li-Resorcinol.

2.2 Vibrational spectra, electronic properties and TDDFT calculations

The Specie BNB and BNB-Li contains 16 atoms and therefore has 42 normal modes of vibration. All the 42 fundamental vibrations are IR active. Theoretical IR spectrum of Boron Nano Bucket (B16), BNB-Li and BNB-Li-Resorcinol are compared in Fig. 2. From Fig. 2 this is clear that BNB-Li system shows some extra intense IR peaks which reveals that more polarity develops due to endrohedral Li doping in BNB. If we again compare BNB-Li system to BNB-Li-Resorcinol, then we find later system have some extra peaks than previous one.

The frontier orbitals, HOMO and LUMO, determine the way the molecule interacts with other species. The frontier orbital gap helps to characterize the chemical reactivity and kinetic stability of the molecule. A molecule which has a larger orbital gap is more polarized having more reactive part as far as reaction is concerned. According to the present calculations, the frontier orbital gap in case of the given structure of B16 is 6.2231 eV, given in Table 2. So we can say that BNB is more reactive than Fullerene (6.59 eV [28]). The plots of the HOMO, LUMO of BNB and BNB-Li are shown in Fig. 3. In BNB, HOMO (Fig. 3a) is located externally over the whole atoms while LUMO is located (Fig. 3a) externally as well as internally over the whole atoms. In BNB-Li both HOMO and LUMO (Fig. 3b) covered whole molecule except Li atom however energy gap in between HOMO and LUMO is 1.82eV (Table 2) which is too short as compared to BNB. This shows that BNB-Li is more reactive as compared to BNB.

Table 2
Calculated $\varepsilon_{\text{HOMO}}$ , $\varepsilon_{\text{LUMO}}$ , energy band gap ( $\varepsilon_{\text{L}}$ – $\varepsilon_{\text{H}}$ ), chemical potential ( $\mu$ ), electronegativity ( $\chi$ ), global hardness ( $\eta$ ), global softness ( $S$ ) and global electrophilicity index ( $\omega$ ) of B16, B15-Li, Reci.B15-Li and Resorcinol by B3LYP/6-311 G (d, p) level

Parameters	$\varepsilon$ ${}_{\text{H}}$	$\varepsilon$ ${}_{\text{L}}$	$\varepsilon$ ${}_{\text{L}}$ – $\varepsilon_{\text{H}}$	$\chi$	$\mu$	$\eta$	$S$	$\omega$
B16	$-$ 7.058	$-$ 0.8345	6.223	3.946	$-$ 3.946	3.112	0.161	2.503
B15-Li	$-$ 5.769	$-$ 3.946	1.823	5.769	$-$ 5.769	0.912	0.549	28.271
Rec.B15-Li	$-$ 5.361	$-$ 3.537	1.824	4.449	$-$ 4.449	0.912	0.548	10.847
Rec	$-$ 5.769	0.190	5.959	2.790	$-$ 2.790	2.980	0.168	1.398

We have also calculated TDDFT on optimized structure of BNB and BNB-Li by using same level of theory. Some intense electronic transitions with their energies of BNB and BNB-Li are listed in Table 3 and theoretical UV spectrum corresponding these transitions is shown in Fig. 4. In these spectra one sharp peak appears at 511 nm in BNB which is due to HOMO $\to$ LUMO (92%) however corresponding peaks shifted towards higher wavelength 593 nm in BNB-Li due to HOMO-1 $\to$ LUMO (95%) transition. On the basis of calculated molecular orbital coefficient analyses, these transitions are due to L ${}_{\text{p}}$ (1) $\to$ L ${}_{\text{p}}$ (2) and L ${}_{\text{p}}^{*}$ (1) $\to$ L ${}_{\text{p}}^{\ast}$ (2) respectively.

Table 3

Calculated electronic transitions: E (eV), oscillatory strength (f), $\lambda_{\max}$ (nm) using TD-DFT/B3LYP/6-311 G (d, p) method of BNB and B15-Li

Species	Electro.Tran.	E (eV)	Oscill.Stre. (f)	Cal. ( $\lambda$ ma)	%Con.	Assignment
B15-Li	HOMO-1 $\to$ LUMO	2.0898	0.1224	593nm	92%	L ${}_{\text{p}}^{*}$ (1) $\to$ L ${}_{\text{p}}^{\ast}$ (2)
	HOMO $\to$ LUMO+1				4%
B16	HOMO $\to$ LUMO	2.4223	0.0052	511nm	95%	L ${}_{\text{p}}$ (1) $\to$ L ${}_{\text{p}}$ (2)

Figure 2.

Comparative IR spectra of Boron Nano Bucket (B16), B15-Li, B15-Li-Resorcinol.

Figure 3.

a. HOMO-LUMO plots of Boron Nano Bucket (B16). b. HOMO-LUMO and plot of Boron Nano Bucket doped-with-Li (B15-Li). c. HOMO-LUMO of Li doped Boron Nano Bucket-interact-with-Resorcinol (B15-Li-Resorcinol).

Figure 4.

Compression of UV plot of BNB with BNB-Li.

2.3 Global reactivity descriptors, NBO, NLO analysis

The energies of frontier molecular orbitals ( $\varepsilon$ HOMO, $\varepsilon$ LUMO), energy band gap ( $\varepsilon$ LUMO – $\varepsilon$ HOMO), electronegativity ( $\chi$ ), chemical potential ( $\mu$ ), global hardness ( $\eta$ ), global softness (S) and global electrophilicity index ( $\omega$ ) [31, 32, 33, 34] of BNB and BNB-Li have been listed in Table 2. On the basis of $\varepsilon$ HOMO, $\varepsilon$ LUMO these parameters are calculated using the Eqs (1)–(5) as given below:

$\displaystyle\chi=-1/2(\varepsilon\text{LUMO}+\varepsilon\text{HOMO})$ (1) $\displaystyle\mu=-\chi=1/2(\varepsilon\text{LUMO}+\varepsilon\text{HOMO})$ (2) $\displaystyle\eta=1/2(\varepsilon\text{LUMO}-\varepsilon\text{HOMO})$ (3) $\displaystyle S=1/2\eta$ (4) $\displaystyle\omega=\mu^{2}/2\eta$ (5)

NBO calculation is a suitable method which gives an effective root for examining charge transfers or conjugative interactions in various molecular schemes [35]. For each acceptor NBO ( $j$ ) and, donor NBO ( $i$ ), the strength of delocalization interaction) E ${}^{(2)}$ [36] is given by Eq. (7).

$\displaystyle E^{(2)}=-q_{i}\frac{(F_{ij})^{2}}{\varepsilon_{j}-\varepsilon_{i}}$ (6)

Where, $q_{i}$ is the inhabitants of donor orbital or donor orbital occupancy; $\varepsilon_{i}$ , $\varepsilon_{j}$ are orbital energies (diagonal elements) of acceptor and donor NBO orbitals respectively; $F_{ij}$ is the off-diagonal Fock or Kohn-Sham matrix element between $i$ and $j$ NBO orbitals. In BNB, an important contribution came from n ${}_{\text{P}}^{*}$ (2) B9 $\to$ n ${}_{\text{P}}^{*}$ (1) B12 which stabilizes BNB by 11.05 kcal/mol while the strongest interaction occurs in between n ${}_{\text{P}}^{*}$ (3) B11 $\to$ n ${}_{\text{P}}^{*}$ (1) B9 which stabilizes BNB by 164.28 kcal/mol. In BNB-Li, two important interaction molecule occurs in between n ${}_{\text{P}}$ (1) B12n ${}_{\text{P}}^{*}$ (1) $\to$ n ${}_{\text{P}}^{*}$ (1) Li16 and n ${}_{\text{P}}^{*}$ (2) B12 $\to$ n ${}_{\text{P}}^{*}$ (4) Li16 which stabilizes BNB-Li by 2.07 kcal/mol and 3.49 kcal/mol respectively. From this analysis (Table 4), this is clear that charge transfer from both bonding and anti-bonding lone pair electrons creates more polarity on BNB-Li rings than BNB.

Table 4

Selected NBO transitions in BNB and B15-Li are calculated by using DFT/B3LYP method

Donor NBO ( $i$ )	Occupancy ( $i$ )	Acceptor NBO ( $j$ )	Occupancy ( $i j$ )	$E$ (2) (kcal/mol)	( $E j$ – $E i$ ) a.u	$F(i,j)$ a.u
B16
L ${}_{\text{P}}^{*}$ (2) B9	0.4937	L ${}_{\text{P}}^{*}$ (1) B12	0.5713	11.05	0.04	0.025
L ${}_{\text{P}}^{*}$ (3) B11	0.6107	L ${}_{\text{P}}^{*}$ (1) B9	0.5710	164.28	0.07	0.127
L ${}_{\text{P}}^{*}$ (3) B11	0.6107	L ${}_{\text{P}}^{*}$ (1) B9	0.5710	164.28	0.07	0.127
B15-Li
L ${}_{\text{P}}$ (1) B12	0.6726	L ${}_{\text{P}}^{*}$ (1) Li16	0.4024	2.07	0.19	0.015
L ${}_{\text{P}}^{*}$ (2) B12	0.4670	L ${}_{\text{P}}^{*}$ (4) Li16	0.1999	3.49	0.10	0.034
CR (1) Li16	1.9733	L ${}_{\text{P}}$ (1) B12	0.6726	1.10	1.92	0.050
CR (1) Li16	1.9733	L ${}_{\text{P}}$ (1) B 6	0.6725	1.10	1.92	0.050

Table 5

Some calculated NLO parameter of BNB and B15-Li

Species	Dipole (D)	Polarizability (a.u.)	Hyper polarizability (a.u.)
B15-Li	3.704	88.68	34.87
B16	0.2068	92.85	1.52

Table 6

Calculated Thermodynamic Properties of BNB and B15-Li by (B3LYP)/6-311 G (d, p) methods

Modes	BNB			B15-Li
	E (Thermal) (kcalmol ${}^{-1}$ )	CV (cal K ${}^{-1}$ mol ${}^{-1}$ )	S (cal K ${}^{-1}$ mol ${}^{-1}$ )	E (Thermal) (kcalmol ${}^{-1}$ )	CV (cal K ${}^{-1}$ mol ${}^{-1}$ )	S (cal K ${}^{-1}$ mol ${}^{-1}$ )
Total	46.905	48.252	99.703	45.924	50.298	104.346
Translational	0.889	2.981	41.406	0.889	2.981	41.337
Rotational	0.889	2.981	30.214	0.889	2.981	30.299
Vibrational	45.127	42.290	28.083	44.146	44.336	32.709

Some NLO parameters like Hyperpolarizability, polarizibility and dipole moment of BNB and BNB-Li have been calculated and are collected in Table 5. From this table, this is clearly shown that NLO activities increases enormously in endrohedral doping of BNB with Li than BNB. The dipole moment of BNB-Li is nearly eighteen times greater than dipole moment of BNB. The calculated Hyperpolarizability of BNB-Li is twenty three times greater than BNB Hyperpolarizability. The Hyperpolarizability BNB-Li is nearly 1.5 times greater than Hyperpolarizability of Urea (0.1947 $\times$ 10 ${}^{-30}$ e.s.u.) therefore the molecule behaves as a good candidate for NLO action. These discussions show that after doping of Li on BNB, resultant system becomes more polarize however both BNB-Li and BNB systems are stable. Calculated Thermodynamic Properties of BNB and B15-Li complex are calculated by (B3LYP)/6-311 G (d, p) methods and are listed in Table 6.

2.4 AIMALL analysis

To check, how B15-Li is used in drug delivery, we have interacted BNB-Li complex to a simple pain killer drug that is Resorcinol. To know the interaction of B15-Li complex with Resorcinol, this is essential to know most electrophilic and most nucleophilic charge centres of B15-Li and Resorcinol. For this we have calculated Fukui function for both species because Fukui function (FF) of any compound gives important information about reactive sites of any compound. Ayers and Parr have clarified that molecules tend to react where the FF is the largest known as soft reagents and in places where the FF is smaller; it is nonreactive site, known as hard reagents [37]. Using the Mulliken atomic charges of neutral, cationic, and anionic state of B15-Li and Resorcinol, we have calculated Fukui functions ( $f_{k}^{+}$ , $f_{k}^{-}$ , $f_{k}^{o}$ ) by using the following Eqs (7)–(9)

$\displaystyle f_{k}^{+}=[q(N+1)-q(N)]\text{ for nucleophilic attack}$ (7) $\displaystyle f_{k}^{-}=[q(N)-q(N-1)]\text{ for electrophilic attack}$ (8) $\displaystyle f_{k}^{o}=1/2[q(N+1)+(N-1)]\text{ for radical attack}$ (9)

Table 7

Calculated Fukui function of BNB-Li and Resorcinol by using DFT/B3LYP method and 6-311 G (d, p)

BNB-Li				Resorcinol
S.N	$f_{k}^{+}$	$f_{k}^{-}$	$f_{k}^{0}$	S.N	$f_{k}^{+}$	$f_{k}^{-}$	$f_{k}^{0}$
1 B	$-$ 0.09902	0.22622	$-$ 0.18257	1C	0.045057	0.028616	0.508209
2 B	0.090185	0.044014	0.023793	2C	0.093329	0.044423	$-$ 0.43287
3 B	$-$ 0.06341	0.139969	0.232576	3C	0.044311	0.026428	0.498973
4 B	$-$ 0.06351	0.140041	0.231147	4C	0.026497	0.093921	$-$ 0.28546
5 B	$-$ 0.04524	0.103059	0.185587	5C	0.030114	0.0657	$-$ 0.30319
6 B	$-$ 0.20232	0.243854	$-$ 0.01078	6C	0.009032	0.092067	$-$ 0.21153
7 B	0.090065	0.044131	0.023834	11O	0.045521	0.098477	$-$ 0.9629
8 B	0.047715	0.121231	$-$ 0.11944	13O	0.044995	0.101795	$-$ 0.96259
9 B	$-$ 0.09851	0.225724	$-$ 0.18262	–	–	–	–
10 B	0.047717	0.121012	$-$ 0.12042	–	–	–	–
11 B	$-$ 0.06301	0.139587	0.232512	–	–	–	–
12 B	$-$ 0.20214	0.243676	$-$ 0.01077	–	–	–	–
13 B	0.04807	0.120644	$-$ 0.12035	–	–	–	–
14 B	0.046885	0.122077	$-$ 0.1195	–	–	–	–
15 B	$-$ 0.06306	0.139607	0.231099	–	–	–	–
16 Li	1.529584	$-$ 1.17485	$-$ 0.2941	–	–	–	–

The calculated value of FF (Table 7) shows that Li is most suitable site for nucleophilic attack while in Resorcinol; O13 atom is most suitable for electrophilic attack. So for interaction of B15-Li with Resorcinol, we put Resorcinol in such a way that doped Li is just closer to O13 of Resorcinol. We have optimized this interactive structure by using combination of DFT/B3LYP method and 6-31 G (d, p) basis set. After optimization, one of O13 of Resorcinol is interacted with doped Li atom with a distance of 1.90A ${}^{0}$ from B15-Li system. The stability of this B15-Li-Resorcinol can be determined by optimized geometry, vibrational analysis, and the binding energy. Vibrational analysis shows that all calculated frequencies are positive. This means, B15-Li-Resorcinol complex shows stable structure. The binding energy of this system is calculated by the given formula

$\displaystyle\Delta\text{E}_{\text{binding}}=\text{E}(\text{BNB-Li})+\text{E}(% \text{Resorcinol})-\text{E}(\text{BNB-Li-Resorcinol})$

The calculated value of $\Delta$ E ${}_{\text{binding}}$ (2.41eV) $>$ 0 shows that BNB-Li-Resorcinol is stable.

To see closer view of BNB-Li interaction with Resorcinol, we have also performed QTAIM analysis of BNB-Li-Resorcinol at BCP. Several topological parameters for bonds of interacting atoms at bond critical point (BCP) are listed in Table 8 and also shown in Fig. 5. The relation in between bond energy ( $\Delta$ E) and (V) at BCP is given by E $=-$ 1/2 V [38]. According to this equation, three important interactions are calculated in BNB-Li-Resorcinol system i.e. O27–Li16, Li16–B12, Li16–B6. The interaction energies of these interactions are 15.844 kcal/mol, 3.169 kcal/mol, 6.62 kcal/mol respectively. From this calculation, we have found that the O27–Li16 interaction is the strongest among all. According to Rozas et al, the nature of O27–Li16 bond in B15-Li-Resorcinol is partially covalent nature due to $\nabla^{2}\rho>$ 0 and $H<$ 0 [39].

Figure 5.

AIM analysis of Li doped Boron Nano Bucket interact with Resorcinol (B15-Li-Resorcinol).

Some electronic parameters of Resorcinol and B15-Li- Resorcinol have been also calculated and listed in Table 2. HOMO-LUMO plots of B15-Li-Resorcinol is shown in Fig. 3C. From this figure, this is shown that HOMO which act primarily donor, located over entire complex however LUMO which acts as primarily acceptor, located over B15-Li complex only. The transition from HOMO $\to$ LUMO shows charge transfer from B15-Li to Resorcinol entity. The value of calculated HOMO-LUMO gap of B15-Li-Resorcinol complex have dropped nearly same value to B15-Li complex than Resorcinol. This means, after interaction of Resorcinol with B15-Li, chemical reactivity does not vary.

Table 8

Topological parameters for bonds of interacting atoms at bond critical point (BCP) of B15-Li-Resorcinol complex

Species	Bond	$\rho_{\text{bcp}}$	$\nabla^{2}\rho_{\text{bcp}}$	V ${}_{\text{bcp}}$	H ${}_{\text{bcp}}$	$E_{\text{in}}$ (Kcal/mol)
B16-Rec	O27-B12	0.0114	0.0496	$-$ 0.0088	0.0018	2.761
	O27-B5	0.0816	0.1916	$-$ 0.0997	$-$ 0.0259	31.281
	O27-B4	0.0867	0.2214	$-$ 0.1145	$-$ 0.0296	35.924
B15-Li-Rec	O27-Li16	0.0305	0.2421	$-$ 0.0505	0.0050	15.844
	Li16-B12	0.0135	0.0583	$-$ 0.0101	0.0022	3.169
	Li16-B6	0.0210	0.1282	$-$ 0.0211	0.0055	6.620
B15-Li-Rec Water solvent	Li16-O27	0.0231	0.1624	$-$ 0.0236	0.0085	7.405
B15-Li-Rec DMSO solvent	Li16-O27	0.0235	0.0162	$-$ 0.0240	0.0083	7.53

Figure 6.

AIM analysis of Li doped Boron Nano Bucket interact with Resorcinol (B15-Li-Resorcinol) in water and DMSO solvent.

In this way, this is easily shown that Resorcinol binds well with the B15-Li complex and binding character is partially covalent or electrovalent in nature. Now, it is easily said that Li doped BNB complex becomes more polarize and hence shows better center for interaction with drug. So it is concluded that B15-Li complex will show better drug delivery potential in upcoming future.

To support our hypothesis, we have performed quantum chemical analysis for B15-Li-Resorcinol in water and DMSO solvent. In this process, this B15-Li-Resorcinol drug complex inter into affected cell in liquid medium. After that, drug delivery system B15-Li complex leave Resorcinol at affected site. To check this, we have again performed AIM analysis for BNB-Li-Resorcinol complex in water and DMSO solvent. These calculated results have been compared with the AIM analysis of BNB-Li-Resorcinol in gaseous medium. These calculated topological parameters and AIM pictures are also listed in Table 8 and Fig. 6 respectively. We have easily seen that O27-Li16 bond is electrovalent in nature because having $\nabla^{2}\rho>$ 0 and $H>$ 0 however interaction strength becomes 8.44 kcal/mol and 8.34 kcal/mol which is much weaker in water and DSMO solvent. These interaction energies in water and DSMO solvent are so small that a small amount of energy is required to break this interaction which may be supplied by human body temperature or other biological activities in the human body. In this way BNB-Li complex leaves the drug Resorcinol into affected cell.

3. Conclusion

In this study, Density Functional Theory has been applied to study theoretical physicochemical properties of newly designed Boron Nano Bucket type structure of B16 and endohedral Li doped B15 complex. The interaction of drug Resorcinol with B15-Li complex was also investigated at the B3LYP/6-311 G (d, p) level of theory. Some interesting outcomes of theoretical calculations are as follows:

According to the obtained results, the interaction of drug Resorcinol with B15-Li complex is an exothermic process and B15-Li-Resorcinol is a stable complex.

It is found that some geometrical parameters of Resorcinol and B15-Li are changed after interaction process due to the formation of intermolecular non-bonded interaction.

NBO analysis predicted charge transfer from both bonding and anti-bonding lone pair electrons of B to Li anti-bonding orbital’s which creates more polarity on BNB-Li rings.

The value of calculated HOMO-LUMO gap of B15-Li-Resorcinol complex have dropped nearly same value to B15-Li complex than Resorcinol. This means, after interaction of Resorcinol with B15-Li, chemical reactivity does not vary.

As a result from AIMALL, this is easily shown that Resorcinol binds well with the B15-Li complex and binding character is partially covalent or electrovalent in nature.

To support our hypothesis, we have also performed quantum chemical analysis for B15-Li-Resorcinol complex in water and DMSO solvent. In this process, this B15-Li-Resorcinol drug complex inter into affected cell in liquid medium.

We hope that our results of the interaction of drug Resorcinol with B15-Li complex will show better drug delivery potential in upcoming future. The lower value of frontier orbital energy gap in case of B16 and B15-Li complex suggests a more reactive nature as compared to fullerene.

Footnotes

Conflict of interest

The authors of manuscript have no conflict of interest in the present work.

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Quantum chemical calculations of a novel Specie – Boron Nano Bucket (B16) and the interaction of its complex (B15-Li) with drug Resorcinol

Abstract

Keywords

1. Introduction

1.1 Computational details

2. Results and discussion

2.1 Optimized equilibrium parameters

Table 1 Bond length and Bond angles of Boron Nano bucket and Li doped BNB by (B3LYP)/6-311 G (d, p) methods

Table 2 Calculated ε HOMO , ε LUMO , energy band gap ( ε L – ε H ), chemical potential ( μ ), electronegativity ( χ ), global hardness ( η ), global softness ( S ) and global electrophilicity index ( ω ) of B16, B15-Li, Reci.B15-Li and Resorcinol by B3LYP/6-311 G (d, p) level

Footnotes

Conflict of interest

References

Table 1
Bond length and Bond angles of Boron Nano bucket and Li doped BNB by (B3LYP)/6-311 G (d, p) methods