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This study spotlights the fundamental insights about the structure and static first hyperpolarizability ( β) of a series of 2,4-dinitrophenol derivatives (1-5), which are designed by novel bridging core modifications. The central bridging core modifications show noteworthy effects to modulate the optical and nonlinear optical properties in these derivatives. The derivative systems show significantly large amplitudes of first hyperpolarizability as compared to parent system 1, which are 4, 46, 66, and 90% larger for systems 2, 3, 4, and 5, respectively, at Moller-Plesset (MP2)/6-31G* level of theory. The static first hyperpolarizability and frequency dependent coupled-perturbed Kohn-Sham first hyperpolarizability are calculated by means of MP2 and density functional theory methods and compared with respective experimental values wherever possible. Using two-level model with full-set of parameters dependence of transition energy (Δ Ε), transition dipole moment ( μ0) as well as change in dipole moment from ground to excited state (Δ μ), the origin of increase in β amplitudes is traced from the change in dipole moment from ground to excited state. The causes of change in dipole moments are further discovered through sum of Mulliken atomic charges and intermolecular charge transfer spotted in frontier molecular orbitals analysis. Additionally, analysis of conformational isomers and UV-Visible spectra has been also performed for all designed derivatives. Thus, our present investigation provides novel and explanatory insights on the chemical nature and origin of intrinsic nonlinear optical (NLO) properties of 2,4-dinitrophenol derivatives. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

In the present work, three complexes(1-Li–NO 2 , 1-Li-Mid and 1-Li–NH 2 ) were designed by doping Li atom into the different location(above, middle and below) of the novel noncovalent “through-space” electronic interaction (S) of Donor-S-Acceptor (1) to explore their structure-property relationships. The results show that doping Li atom can obviously enhance the first hyperpolarizability (β tot) of 1. Interestingly, the crucial transition direction of 1-Li–NH 2 is from donor group to acceptor group, which is opposite to those of 1-Li–NO 2 and 1-Li-Mid. The highest occupied molecular orbital (HOMO) of 1-Li–NH 2 shows that doping one Li atom enhances the π–π interaction resulting in the largest β tot value (1.50 × 105) which is about 16 times larger than that of 1(9.13 × 103) and is also obviously larger than those of 1-Li-Mid(5.81 × 104) and 1-Li–NO 2 (6.45 × 104 au). The results indicate that 1-Li–NH 2 can be considered as a novel high-performance NLO material and the location of Li atom can modulate NLO response. [ABSTRACT FROM AUTHOR]

Möbius strip has attracted extensive interest due to its one-side structure, special physical and chemical properties. A new extended porphyrin with Möbius structure has been synthesized (Stępień et al., Angew. Chem. Int. Ed. 2007, 46, 7869). In this work, an electron is injected into Möbius to form Möbius anion. For Möbius, four methods (B3LYP, BHandHLYP, CAM-B3LYP, and LC-BLYP) obtain the similar first hyperpolarizability ( β0). However, for Möbius anion, four methods obtain very different β0 values (ranging from 9.85 × 103 to 8.33 × 105 au). Moreover, the β0 values of Möbius anion are larger than those of Möbius. Why? The considerable variation (ranging from 0.8162 to 1.7630) of spin contamination ( S2) of open-shell Möbius anion captures our attention. To probe the relationship between S2 and β0, the β0 values of Möbius anion were calculated using 23 methods. Interestingly, the Hartree-Fock (HF) composition increases from 0 to 50, the S2 value ranges from 0.7522 to 1.3372, and the β0 value increases from 4.3 × 103 to 7.36 × 104 au. Further, methods are 'dissected' to investigate the effect of HF composition on the S2. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

In this work, we add different strength of external electric field ( Eext) along molecule axis (Z-axis) to investigate the electric field induced effect on HArF structure. The H-Ar bond is the shortest at Eext = −189 × 10−4 and the Ar-F bond show shortest value at Eext = 185 × 10−4 au. Furthermore, the wiberg bond index analyses show that with the variation of HArF structure, the covalent bond H-Ar shows downtrend (ranging from0.79 to 0.69) and ionic bond Ar-F shows uptrend (ranging from 0.04 to 0.17). Interestingly, the natural bond orbital analyses show that the charges of F atom range from −0.961 to −0.771 and the charges of H atoms range from 0.402 to 0.246. Due to weakened charge transfer, the first hyperpolarizability (βtot) can be modulated from 4078 to 1087 au. On the other hand, make our results more useful to experimentalists, the frequency-dependent first hyperpolarizabilities were investigated by the coupled perturbed Hartree-Fork method. We hope that this work may offer a new idea for application of noble-gas hydrides. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Six N-substituted [ n]cyclacene ( n = 5, 6, 7,...,10) molecules were designed to study the relationship between the structure and first hyperpolarizability. Their static first hyperpolarizabilities ( β0) were obtained by MP2/6-31 + g(d) level. Two interesting relationships between the β0 value and the structure have been found: (1) The β0 value increases with the increase of the number n when n is odd: 3155 ([5]cyclacene) < 48,905 ([7]cyclacene) < < 393,444 ([9]cyclacene), and when n is even: 357,620 ([6]cyclacene) < 618,608 ([8]cyclacene) < 3,513,644 a.u. ([10]cyclacene). (2) The β0 values (in the range of 357,620 ~ 3,513,644 a.u.) of the N-substituted [ n]cyclacene (when n is odd) are much larger (in the range of 3155~393,444 a.u.) than that of the N-substituted [ n]cyclacene (when n is even). Furthermore, their frequency-dependent β (−2ω; ω, ω) and β (−ω; ω, 0) (ω = 0.005, 0.01, and 0.0239 a.u.) were also estimated by Møller-Plesset perturbation/6-31 + g(d) level. Among the frequency-dependent β (ω), [10]cyclacene has the largest β (−ω; ω, 0) and β (−2ω; ω, ω) to be 1.2 × 108 (ω = 0.01) and 2.9 × 107 a.u. (ω = 0.005 a.u.), which are much larger than the static β0 = 3.5 × 106 a.u. by 34 and 8 times. Our present work may offer a new idea in the design of high-performance tubiform nonlinear optical materials. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In our previous work, new alkalides Li+(calix [4]pyrrole)M− with cup‐like complexant have been reported for the large static first hyperpolarizabilities (β0) (Chen et al., J Am Chem Soc 2006, 128, 1072). In this work, new inorganic alkalides are found by using a more flexible complexant, methylamine (NH2CH3)4. The structures with all real frequencies and β0 values of the inorganic alkalides Li+(cage [4]methylamine)M− (M = Li, Na, and K) are obtained at MP2 level. The result shows that these inorganic alkalides have more considerable β0 values to be 18,825 (M = Li) < 27,942 (M = Na) < 81,094 au (M = K), which are more than two times larger than those (10,969 ∼ 35,934 au) of the reported alkalides Li+(calix [4]pyrrole)M−. To understand this structure–property relationship, two cup‐like Li+(NH2CH3)4M− (M = Li, Na, and K) models are designed to compare their β0 values. By comparing the β0 values among the cup‐like alkalides Li+(calix [4]pyrrole)M−, Li+(NH2CH3)4M−, and cage‐like alkalides Li+(cage [4]methylamine)M− (M = Li, Na, and K), the complexant shape effect of alkalides has been revealed. It is found that the complexant shape is an important factor in large β0 values. Moreover, the monotonic dependences of β0 on the Li–M distance and the NBO charges of cation (Li+) and anions (M−) in inorganic alkalides Li+(cage [4]methylamine)M− have been shown. In this work, the frequency dependent first (hyper)polarizabilities are also determined. It is found that both the frequency dispersion and the effects of the electron correlation are strong. Moreover, the dependence of both the static and frequency dependent β on the atomic number of alkali metal anions is similar. This work provides a new way to understand the nature of high‐performance nonlinear optical (NLO) materials, and it is helpful to design new NLO materials. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011. [ABSTRACT FROM AUTHOR]

It is well known that settling transparency-efficiency tradeoff is important to design nonlinear optical (NLO) materials. In this work, we constructed one-dimensional polymeric cyanoacetylene (N C C C H) n by hydrogen-bond-directed-linking to understand this tradeoff from molecular level. Results show that the first hyperpolarizability of (N C C C H) n ( n = 2–8) gradually increased with the increase of n , and what is more important is that the red-shifts, associated with the increase of n , were very little. It is proposed that these polymeric structures possess double-degenerated charge transitions, which contribute to the hyperpolarizability in an additive fashion, and that the coupled oscillators are gradually improved, which lead to the increase of the first hyperpolarizability. Therefore, we propose the hydrogen-bond-directed-linking idea is helpful to develop the potential high-performance NLO materials. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate the recognition of cations by complexation of N-(O -methoxyphenyl)aza-15-crown-5-ether derivative (TZC) with alkali (Li+, Na+, K+), alkaline earth (Mg2+, Ca2+) and transition metal cations (Ni2+, Zn2+). The doping of mono- and divalent metal cations are used to significantly enhance the first hyperpolarizability values as compared to TZC. By utilizing density functional (DFT) methods, the parent molecule and metal-doped complexes have been optimized using B3LYP-D3/6-31G* level of theory. The amplitudes of first hyperpolarizability β tot have been obtained CAM-B3LYP and M06-2X functional for all studied systems. Interestingly, the atomic number, size, and charge of the metal cations and the O- and N-atoms of the crown-ether are found to be the major factor that gives rise to higher NLO response properties. From the natural bond orbital (NBO), localized orbital locator (LOL) and interactional energy analyses, alkali metal cations possessing a higher degree of ionic characteristics, whereas, the alkaline earth and transition metal cations possessing significant covalent characters. Furthermore, the frontier molecular orbital analysis and the TD-DFT studies reveal that the transition energies as a function of metal size and charge are responsible for remarkably enhanced and distinctive β tot amplitudes as large as TZC-Li+ 10,158 a.u., TZC-Mg2+ 21,948 a.u. and TZC-Ni2+ 25,483 a.u. Additionally, the electrostatic potential maps (ESP) and the difference of dipole moments (Δ μ) from the ground to the first excited state have also been carried out to understand the abilities of these systems as highly efficient and selective metal cation sensors. The quantum chemical investigation of the β tot amplitudes enhancement for TZC chromophore upon doping of alkali, alkaline earth, and transition metal ions. Unlabelled Image • NLO based metal sensing of N-(O -methoxyphenyl)aza-15-crown-5-ether derivatives • Higher NLO response with β tot values at Li+ 10,157, Mg2+ 21,946 and Ni2+ 25,482 a.u. • The E int , NBO and LOL analyses elucidate the ether cavity and radius of metal ions. • β tot values justified through the transition energies by TD-TDF and FMO analyses • The transition energies trends are Li+ < Na+ < K+, Mg2+ < Ca2+ and Ni2+ < Zn2+. [ABSTRACT FROM AUTHOR]

Structure of (M+@C 50 N 5 H 5)Mʹ−(M = Li and Na; Mʹ = Li, Na, and K) with alkalides characteristics and large nonlinear optical response. [Display omitted] • In this work, a novel type of compound (M+@C 50 N 5 H 5)Mʹ−(M = Li and Na; Mʹ = Li, Na, and K) was designed. • Their alkalides' properties are confirmed by their FMO and NPA charges analysis. • The proposed alkalides exhibited considerable first hyperpolarizability up to 1.91 × 105 a.u. Based on open-cage fullerenes C 50 N 5 H 5 , a novel type of compounds (M+@C 50 N 5 H 5)Mʹ− (M = Li, Na; Mʹ = Li, Na and K) was designed and studied. Firstly, their alkalides' properties are confirmed by their FMO and NPA charges analysis. In particular, the proposed alkalides exhibited considerable first hyperpolarizability (β 0) up to 1.91 × 105 a.u., which indicated that they could be regarded as high-performance novel NLO molecules. These alkalides will pave the way for further exploration of electronic-stable, high-performance NLO materials. [ABSTRACT FROM AUTHOR]