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Recently, an anthraquinone-supported thiourea group linking a 1-aza-18-crown-6 macrocycle L has been the subject of extensive attention due to the perfect affinity towards metal cations. This work systematically researched the effects of different metal cations (M = Na + , K + , Mg 2 + , Ca 2 + , Cu + and Ag + ) on the second-order nonlinear optical (NLO) properties of macrocycle L by density functional theory (DFT). DFT calculations revealed that the values of first hyperpolarizabilities ( β tot ) decrease significantly when alkaline earth metal cations ( Mg 2 + and Ca 2 + ) were injected into macrocycle L due to the smaller charge transfer (CT) transition and larger transition energy. Conversely, the variations of β tot values in alkali metal cations ( Na + and K +) and transition metal cations ( Cu + and Ag + ) derivatives are not obvious compared to the β tot value of macrocycle L. Therefore, the NLO properties of macrocycle can be effectively regulated by alkaline earth metal cations. Furthermore, we found that the β tot value of anion-controlled complex Na(L)(ClO4) is larger than that of L*Na+ complex because the anion ClO 4 − improves the planarity of anthraquinone-supported thiourea group leading to the enhancement of the CT ability. In addition, the influence of frequency-dependent on the first hyperpolarizabilities is weak for the current systems. Hence, we look forward to the conception of this work will offer a fundamental guideline and reference for further research for novel NLO materials. The second-order NLO properties of the macrocycle L can be regulated availably by alkaline earth metal cations (Mg2+ and Ca2+). The introduction of anions can also be used as a strategy to adjust the NLO response of studied system. Geometric construction, CT ablitiy and transition energy are the important factors to impact the NLO properties. [ABSTRACT FROM AUTHOR]

In this paper, a series of cationic iridium complexes [(2-phenylpyridine)2(2,2 ′ -bipyridine)Ir] + which substituted phenyl on different ligands position have been systematically investigated by density functional theory (DFT) method. Significantly, the first hyperpolarizability β tot values can be enhanced by introducing phenyl on 2-phenylpyridine ligands R1 or R2, whereas substituting phenyl on 2,2 ′ -bipyridine ligands R3 result in a decreasing β tot values. The β tot values exhibit obvious connection with the corresponding HOMO and LUMO energy gap. Furthermore, the time-dependent (TD) DFT calculations suggest that the enhanced β tot values are related to obvious charge transfer from 2-phenylpyridine ligands to 2,2 ′ -bipyridine ligands. The investigation of frequency-dependent first hyperpolarizability β (− ω ; ω , 0) and β (− 2 ω ; ω , ω) shown less dispersion effect at the low-frequency region for all of the studied complexes. Overall, tuning phenyl on the different ligands position can be seen as an effective strategy to modulate the second-order nonlinear optical response for these iridium complexes, which is benefit to theoretical and experimental further investigation. The study of serial [(2-phenylpyridine)2(2,2′-bipyridine)Ir]+ complexes reveal that the second-order NLO properties can be effectively modulated by introducing phenyl on different ligands position. Thereinto, the first hyperpolarizability βtot values can be enhanced by introducing phenyl on R1 or R2, whereas substituting phenyl on R3 result in a decreasing βtot values. [ABSTRACT FROM AUTHOR]