Utilization of hepatitis B surface antigen-positive donors in liver transplantation for recipients with hepatocellular carcinoma: a retrospective and propensity score matching analysis.

Introduction: The use of extended criteria donor (ECD) grafts such as donor with infection of hepatitis B virus (HBV) is a potential solution for organ shortage. In this study, we aimed to evaluate the safety and long-term survival of utilization of hepatitis B surface antigen-positive (HBsAg+) donor livers in HCC patients using propensity score matching (PSM) analysis. Methods: Forty-eight donors with HBsAg-positive and 279 donors with HBsAg-negative were transplanted and enrolled in this study. PSM analysis were used to eliminate selection bias. Perioperative data and survival were collected and analyzed. Results: PSM generated 44 patient pairs. When comparing intra- and post-operative data, no significant difference was found between groups (P > 0.05). Patients with a HBsAg-positive donor had significantly worse progression-free survival (1-year: 65.9% vs. 90.9%; 3-year: 18.1% vs. 70.4%, P = 0.0060) and overall survival (1-year: 84.1% and 95.4%; 3-year: 27.2% vs. 79.5%, P = 0.0039). In multivariate analysis, donor HBsAg-positivity was an independent risk factor for survival and occurrence (P = 0.005 and 0.025, respectively). Conclusion: In conclusion, with adequate antiviral prophylaxis and treatment, utilization of HBsAg positive liver grafts did not increase the incidence of early-stage complications. However, patient with an HBsAg-positive graft had poorer progression-free survival and overall survival.

Ultrastructural changes of donor livers in liver transplantation indicate hepatocytes injury.

The use of electron microscopy (EM) can provide details about cells and tissue down to the nanometer level. We aim to observe ultrastructural changes in the donor liver by EM and analyze the relationship with prognosis. Data from 89 liver transplant recipients were collected and analyzed for recovery of graft function. The results revealed significantly higher organelle injury scores in the primary liver graft nonfunction (PNF) group. High-score group had higher peak alanine aminotransferases, peak aspartate aminotransferases, and peak international normalized ratio (p = .041, .006 and .036, respectively). Warm ischemia time, score of rough endoplasmic reticulum and nucleus was larger in low-score group (p = .007, .006, and .025, respectively). Patients in high-score group had a significantly short survival time (60.0% vs. 92.9%, p = .0039). No significant difference was found in the analysis of 3-year survival rate (60% vs. 84.5%, p = .07). EM is one of feasible and effective strategy for evaluating the quality of donor liver and the patient's prognosis. Ultrastructural changes under EM indicate hepatocytes injury and a high score indicates a worse outcome in early period but does not affect long-term survival. RESEARCH HIGHLIGHTS: We showed that ultrastructural changes in the donor liver by electron microscopy indicate hepatocytes injury and could be a reference for prognosis. A high score indicates a worse outcome in early period but does not affect long-term survival. It is rare in the current researches.

Transplantation of Extended Criteria Donor Livers Following Continuous Normothermic Machine Perfusion Without Recooling.

BACKGROUND: Traditional liver transplant strategies with cold preservation usually result in ischemia-reperfusion injury (IRI) to the donor liver. Regular normothermic machine perfusion (NMP) donor livers suffer IRI twice. Here, we aimed to introduce a novel technique called continuous NMP without recooling to avoid a second IRI and its application in livers from extended criteria donors. METHODS: Seven donor livers transplanted following continuous NMP without recooling, 7 donor livers transplanted following standard NMP, and 14 livers under static cold storage (SCS) were included in this study. Perioperative outcomes were recorded and analyzed between groups. RESULTS: During the NMP without a recooling procedure, all livers cleared lactate quickly to normal levels in a median time of 100 min (interquartile range, 60-180) and remained stable until the end of perfusion. In the NMP without recooling and standard NMP groups, posttransplant peak aspartate aminotransferase and alanine aminotransferase levels were both significantly lower than those in the SCS group (P = 0.0015 and 0.016, respectively). The occurrence rate of early allograft dysfunction was significantly lower in the NMP without recooling group than in the SCS group (P = 0.022), whereas there was no difference in the NMP group with or without recooling (P = 0.462). CONCLUSIONS: Our pilot study revealed a novel technique designed to avoid secondary IRI. This novel technique is shown to have at least a comparable effect on the standard NMP, although more data are needed to show its superiority in the future.

Application of various surgical techniques in liver transplantation: a retrospective study.

BACKGROUND: Surgical techniques of liver transplantation have continually evolved and have been modified. We retrospectively analyzed a single-center case series and compared the advantages and disadvantages of each method. METHODS: Six-hundred and seventy-four recipients' perioperative data were assessed and analyzed stratified by different surgical technics [modified classic (MC), modified piggyback (MPB) and classic piggyback (CPB)]. RESULTS: MELD score and Child-Pugh scores was significantly higher in CPB groups (P=0.008 and 0.003, respectively). Anhepatic time in MPB group was longer than those in CPB group (P<0.05). The operation duration in MPB group was significantly longer than those in MC group and CPB group (P=0.003). Three patients had outflow obstruction (P=0.035). The overall survival in MPB group were better than those in MC group and CPB group in general comparison (P<0.001). In patients with preoperative creatine >120 µmol/L, the overall survival in MC group was worst (P<0.001). In patients with a high MELD score (>24), the overall survival in MPB group tended to be the best (P<0.001). CONCLUSIONS: The advantages and disadvantages are different for these three surgical techniques. A reasonable operation technique should be adopted considering the patient's unique condition to ensure the stability of hemodynamics.

Circulating Tumor Cell Is a Clinical Indicator of Pretransplant Radiofrequency Ablation for Patients with Hepatocellular Carcinoma.

INTRODUCTION: It is of great significance to confirm reliable indicators for the guidance of pretransplant radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). In this study, we aim to investigate whether circulating tumor cell (CTC) status is a clinical indicator for RFA before liver transplantation (LT) in HCC patients. METHOD: CTC analyses were measured in 79 HCC patients. Clinical outcomes including progression-free (PFS) and overall survival (OS) were compared and analyzed between patients with and without pretransplant RFA. RESULT: Forty-two patients were detected as CTC-positive and 18 patients received pretransplant RFA. Recurrence was correlated with CTC count (P=0.024), tumor number (P=0.035), liver cirrhosis (P=0.001), Milan criteria (P=0.003), and University of California San Francisco (UCSF) criteria (P=0.001). Kaplan-Meier analysis revealed that patients with CTC-positive had a lower PFS rate (P=0.0257). For CTC-positive patients, the PFS rate of the pretransplant RFA group was significantly higher than the non-pretransplant RFA group (100% vs. 46.7%, P=0.0236). For CTC-negative patients, both PFS rate and OS rate were similar and without significant differences. In multivariate analysis, pretransplant RFA was the independent factor for PFS (P=0.025). CONCLUSION: Pretransplant CTC status can guide the administration of pretransplant RFA in HCC patients which can improve PFS in CTC-positive HCC patients.

En bloc procurement of porcine abdominal multiple organ block for ex situ normothermic machine perfusion: a technique for avoiding initial cold preservation.

BACKGROUND: Normothermic machine perfusion (NMP) is a technique that maintains organs ex situ with normal metabolism, and organ function can be better preserved. The study of multiple-organ NMP is rarely reported. Multiple organ block (MOB) is a self-perfusing system for maintaining multiple organs ex situ, and porcine MOBs have been successfully preserved for 18 to 37 h. Due to the above context, we conceived to maintain abdominal multiple organ block (AMOB) ex situ utilizing NMP technology. METHODS: AMOBs were procured from Ba-Ma miniature pigs through en bloc procurement surgery. The process of cold preservation was eliminated between the procurement and machine perfusion, and a few minutes of warm ischemia emerged. Autologous whole blood was collected during procurement surgery as a perfusate component in the beginning. RESULTS: The median time of procurement surgery was approximately 220 min, and the median time of warm ischemia was 300 sec. Cases 1 and 2 suffered from repeated hypotension during the procurement surgery, and case 2 exhibited hemorrhage. After improved and optimized procurement processes, the vital signs of cases 3 to 5 remained stable during procurement. In the NMP phase, the flow increased slowly in cases 1 and 2 and did not remain stable even after continuous infusion of a high-dose vasodilator. The lactic acid level rapidly increased, and the levels of ALT and AST were obviously higher than those in cases 3 to 5. In contrast, the flow rate increased smoothly in cases 3 to 5. The lactic acid level remained stable during the first 10 h of perfusion. CONCLUSIONS: AMOB procurement from heart-beating pigs for NMP without initial cold preservation is technically feasible.

Analysis of preoperative circulating tumor cells for recurrence in patients with hepatocellular carcinoma after liver transplantation.

BACKGROUND: Liver transplantation (LT) is an effective option for hepatocellular carcinoma (HCC) and end-stage liver cirrhosis. However, organ shortage and tumor recurrence are the main obstacles limiting its popularization and application in HCC patients. Testing for circulating tumor cells (CTCs) would be a valuable strategy to predict the recurrence and metastasis of HCC after LT. Various CTCs detection methods have different advantages and disadvantages. This study aims to investigate the predictive value of testing for CTCs based on immunofluorescence in situ hybridization of peripheral blood cells in patients with HCC after LT. METHODS: A total of 50 patients who received testing for CTCs and then underwent LT were enrolled in this study. Negative enrichment and immunofluorescence in situ hybridization (imFISH) methods were introduced to detect CTCs. RESULTS: Twenty-six (52%) patients were CTC-positive, and 24 (48%) patients were CTC-negative. The results showed that CTCs result was correlated with tumor size (ꭓ2=5.773, P=0.016), AFP level (ꭓ2=5.454, P=0.020), tumor grade (ꭓ2=6.478, P=0.039) and Recurrence(ꭓ2=6.211, P=0.013).Twelve patients had recurrence after LT within one year. The results showed that the CTCs result (P=0.034) was the only independent factor impacting long-term survival. The 1-year disease-free survival rates of CTC-negative and CTC-positive patients were 91.6% and 61.5%, respectively (P=0.020). The 1-year overall survival of CTC-positive patients and CTC-negative was 88.5% and 91.7%, respectively (P=0.751). CONCLUSIONS: CTCs result was closely related to the early recurrence of patients with HCC after LT. CTC-positive patients had a worse prognosis after LT than the CTC-negative group.

The First Case of Ischemia-Free Kidney Transplantation in Humans.

Background: Ischemia-reperfusion injury (IRI) has been considered an inevitable event in organ transplantation since the first successful kidney transplant was performed in 1954. To avoid IRI, we have established a novel procedure called ischemia-free organ transplantation. Here, we describe the first case of ischemia-free kidney transplantation (IFKT). Materials and Methods: The kidney graft was donated by a 19-year-old brain-dead donor. The recipient was a 47-year-old man with end-stage diabetic nephropathy. The graft was procured, preserved, and implanted without cessation of blood supply using normothermic machine perfusion. Results: The graft appearance, perfusion flow, and urine production suggested that the kidney was functioning well-during the whole procedure. The creatinine dropped rapidly to normal range within 3 days post-transplantation. The levels of serum renal injury markers were low post-transplantation. No rejection or vascular or infectious complications occurred. The patient had an uneventful recovery. Conclusion: This paper marks the first case of IFKT in humans. This innovation may offer a unique solution to optimizing transplant outcomes in kidney transplantation.

MicroRNA-423-5p facilitates hypoxia/reoxygenation-induced apoptosis in renal proximal tubular epithelial cells by targeting GSTM1 via endoplasmic reticulum stress.

It has been reported that microRNAs (miRs) can regulate renal response to acute injury and members of them are believed to be important in maintenance of renal function and development of renal injury. We investigated the actions of microRNA-423-5p (miR-423-5p) and glutathione-S-transferase (GST) M1 after acute kidney injury. MiR-423-5p was up-regulated and GSTM1 was down-regulated in human kidney (HK-2) cells subjected to hypoxia/reoxygenation (H/R) and in rat kidneys subjected to ischemia/reperfusion (I/R) injury. Dual luciferase assays revealed miR-423-5p binding to the 3' untranslated region of GSTM1. Proliferation was lower and apoptosis, ER stress and oxidative stress were all higher in H/R-treated HK-2 cells transfected with or without miR-423-5p mimics and GSTM1 siRNA than in the same cells transfected with miR-423-5p inhibitors and a GSTM1 expression vector. Increased miR-423-5p and decreased GSTM1 mRNA and protein levels were observed in rat kidneys on days 1, 2 and 7 after I/R. Levels had normalized by days 14 and 21. On day 3 after treatment, rats receiving I/R or I/R plus miR-423-5p mimics exhibited higher serum creatinine and urea nitrogen levels than rats receiving I/R plus a miR-423-5p inhibitor. MiR-423-5p and lower GSTM1 mRNA and protein levels were higher in the I/R and I/R plus miR-423-5p mimic groups than in the I/R plus miR-423-5p inhibitors group. These findings demonstrate that after acute kidney injury, miR-423-5p induces ER stress and oxidative stress by inhibiting GSTM1and suppresses repair.

Anisodamine inhibits endoplasmic reticulum stress-associated TXNIP/NLRP3 inflammasome activation in rhabdomyolysis-induced acute kidney injury.

Anisodamine protects against free radical-induced cellular damage. This study aimed to investigate the protective effect of anisodamine on rhabdomyolysis-induced acute kidney injury (RIAKI). C57BL/6 J mice, TXNIP-/- and NLRP3 -/- (both were C57BL/6 J background) mice were used to construct RIAKI model. Anisodamine administration was performed on RIAKI mice only. Mice were divided into control, TXNIP-KD (knock down), LNPR3-KD, and anisodamine group (n = 15 in each group). The renal injury, renal function, renal tubular cells apoptosis and expression of Caspase-1, ASC, endoplasmic reticulum (ER) stress markers IRE-1α, CHOP, and ATF4, and interleukin (IL-1α, IL-1ß, and IL-18) were detected. The knock down of TXNIP or NLRP3 expression in mice showed protective effect against RIAKI pathogenesis, as compared with the RIAKI mice. The expression of Caspase-1, ASC, and interleukins, renal injury, renal tubular cells apoptosis in TXNIP-KD and LNPR3-KD mice were significantly inhibited in comparison with the RIAKI mice. Moreover, anisodamine treatment reduced expression of ER stress markers IRE-1α, CHOP, and ATF4, TXNIP and NLRP3, as well as ACS, Caspase-1, IL-1α, IL-1ß, and IL-18, showing moderate protective effect on the changes of above factors comparing with TXNIP or NLRP3 knock down. This study declared that anisodamine showed protective effect on RIAKI model may by inhibiting ER stress associated TXNIP/NLRP3 inflammasome.

Kidney transplantation from donors with rhabdomyolysis and acute renal failure.

Rhabdomyolysis in deceased donors usually causes acute renal failure (ARF), which may be considered a contraindication for kidney transplantation. From January 2012 to December 2016, 30 kidneys from 15 deceased donors with severe rhabdomyolysis and ARF were accepted for transplantation at our center. The peak serum creatinine (SCr) kinase, myoglobin, and SCr of the these donors were 15 569±8597 U/L, 37 092±42 100 µg/L, and 422±167 µmol/L, respectively. Two donors received continuous renal replacement therapy due to anuria. Six kidneys exhibited a discolored appearance (from brown to glossy black) due to myoglobin casts. The kidney transplant results from the donors with rhabdomyolysis donors were compared with those of 90 renal grafts from standard criteria donors (SCD). The estimated glomerular filtration rate at 2 years was similar between kidney transplants from donors with rhabdomyolysis and SCD (70.3±14.6 mL/min/1.73 m2 vs 72.3±15.1 mL/min/1.73 m2 ). We conclude that excellent graft function can be achieved from kidneys donors with ARF caused by rhabdomyolysis.

Renal Transplantation Using Stone-bearing Deceased Donor Kidneys-Experience of a Transplant Center in China.

OBJECTIVE: To evaluate the outcomes of transplantation of deceased donor stone-bearing kidneys. METHODS: A total of 32 patients who received renal transplantation at our center from July 2011 to June 2016 were included. Eight recipients received kidneys with incidental renal stone(s) (stone group). Twenty-four recipients received kidneys without renal stones (non-stone group). The transplantation outcomes of the 2 groups were compared. RESULTS: There was 1 case of postoperative urinary tract infection in the stone group, and 2 cases in the non-stone group. No ureteral obstruction or hydronephrosis occurred in either group. No significant difference was found in the incidence of complications, serum creatinine level, and estimated glomerular filtration rate between the groups (all, P >.05). No deaths occurred in either group during the follow-up period. One recipient had postoperative calculi recurrence, and 4 recipients had residual calculi before transplantation. However, these patients had no symptomatic nephrolithiasis or obstruction, and their renal functions were normal. CONCLUSION: Transplantation of deceased donor stone-bearing kidneys can achieve comparable outcomes of deceased donor non-stone-bearing kidneys.

Bone mesenchymal stem cells ameliorate ischemia/reperfusion-induced damage in renal epithelial cells via microRNA-223.

BACKGROUND: Recent studies have indicated that microRNA-223 (miR-223) plays a role in the tissue-protective effect of mesenchymal stem cells (MSCs). NLR family-pyrin domain containing 3 (NLRP3) was reported to affect a renal ischemia/reperfusion (I/R) injury by exerting a direct effect on the renal tubular epithelium. Therefore, we investigated how miR-223 and NLRP3 might function in kidneys exposed to conditions of ischemia and subsequent reperfusion. METHODS: Hypoxia/reoxygenation (H/R) murine renal tubular epithelial cells (RTECs) were cocultured with either MSCs or hypoxia-pretreated MSCs (htMSCs), after which the RTECs were examined for their viability and evidence of apoptosis. Next, miR-223 expression in the MSCs was downregulated to verify that MSCs protected RTECs via the transport of miR-223. Kidney I/R KM/NIH mouse models were created and used for in vivo studies. RESULTS: The results showed that coculture with MSCs significantly increased the viability of RTECs and decreased their rates of apoptosis. The levels of hepatocyte growth factor (HGF), insulin-like growth factor-1 (IGF-1), transforming growth factor beta (TGF-ß), and vascular endothelial growth factor (VEGF) in samples of coculture supernatants were higher than those in samples of non-coculture supernatants. A bioinformatics analysis revealed a targeting relationship between miR-223 and NLRP3. A dual luciferase assay showed that miR-223 inhibited NLRP3 expression. The htMSCs displayed a protective function associated with an upregulation of miR-223 as induced by Notch1 and the downregulation of NLRP3. Conversely, inhibition of miR-223 impeded the protective effect of MSCs. In the I/R mouse models, injection of either MSCs or htMSCs ameliorated the damage to kidney tissue, while suppression of miR-223 expression in MSCs reduced their protective effect on mouse kidneys. CONCLUSIONS: Our results demonstrate that miR-223 and NLRP3 play important roles in the treatment of renal tissue injuries with transplanted MSCs.

Up-Regulation of HMGB1 Exacerbates Renal Ischemia-Reperfusion Injury by Stimulating Inflammatory and Immune Responses through the TLR4 Signaling Pathway in Mice.

BACKGROUND/AIMS: The aim of this study was to elucidate how high-mobility group box 1 (HMGB1) exacerbates renal ischemic-reperfusion injury (IRI) by inflammatory and immune responses through the toll-like receptor 4 (TLR4) signaling pathway. METHODS: A total of 30 wild-type (WT) mice and 30 TLR4 knockout (TLR4-/-) mice were selected and then randomly assigned to the Sham, I/R or HMGB1 groups. The serum and kidney tissues of all mice were collected 24 h after the perfusion. The fully automatic biochemical detector and ELISA were applied to determine the blood urea nitrogen (BUN) and serum creatinine (Scr) levels, and TNF-α, IL-1ß, IL-6, IFN-γ and IL-10 levels, respectively. HE staining was used to evaluate kidney tissue damage, immunofluorescence and immunohistochemical staining were performed to observe CD68 and MPO cell infiltration, and flow cytometry was applied to detect immune cells. qRT-PCR and Western blotting were used to detect the expressions of TLR signaling pathway-related genes and proteins, respectively. RESULTS: Compared with the Sham group, the levels of BUN, Scr, TNF-α, IL-1ß, IL-6, IFN-γ and IL-10, kidney tissue damage score, CD68 and MPO cell infiltration, the numbers of immune cells, and the expressions of TLR signaling pathway-related genes and proteins in the I/R and HMGB1 groups were significantly up-regulated. In the I/R and HMGB1 groups, the levels of BUN and Scr, TNF-α, IL-1ß, IL-6 and IFN-γ, kidney tissue damage score, CD68 and MPO cell infiltration, immune cell numbers, and TLR signaling pathway-related gene and protein expressions in the WT mice were all higher than those in the TLR4-/- mice, but IL-10 level was significantly lower. Similarly, all aforementioned indexes but IL-10 level in the WT and TLR4-/- mice were higher in the HMGB1 group than in the I/R group. CONCLUSION: Our study indicated that the up-regulation of HMGB1 could exacerbate renal IRI by stimulating inflammatory and immune responses through the TLR4 signaling pathway.c.

MicroRNA-34a regulates liver regeneration and the development of liver cancer in rats by targeting Notch signaling pathway.

OBJECTIVE: This study aimed to investigate the role of microRNA-34a (miR-34a) in regulating liver regeneration (LR) and the development of liver cancer in rats by targeting Notch signaling pathway. METHODS: Thirty male Sprague-Dawley (SD) rats were randomly assigned into partial hepatectomy (PH) group and sham hepatectomy (SH) group. Hematoxylin and eosin (HE) staining was used to observe the histological change in liver tissues. Enzyme-linked immunosorbent assay (ELISA) was used to measure the serum tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) levels. Dual-luciferase reporter gene assay was performed to examine whether miR-34a targeted Notch1 gene. Human liver cancer Huh7 cells were transfected and divided into blank, negative control (NC), miR-34a mimics and miR-34a inhibitors groups. MTT and flow cytometry were used to detect cell growth, and cell cycle and apoptosis, respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) was applied detect to the expressions of miR-34a and Notch receptor mRNA. Western blotting was performed to detect the protein expressions of Notch receptors, P21, Bax, Bcl-2 and Bcl-xL. Tumor xenograft in nude mice was done to observe tumor formation in different groups. RESULTS: Compared to the SH group, miR-34a expression in liver tissues in the PH group decreased first and then increased to the normal level during LR. In early stage of LR, the expressions of Notch receptors and miR-34a were negatively correlated. Compared to the blank and NC groups, the cell growth was inhibited, cell cycle was mainly arrested in the G2/M phase and cell apoptosis rate increased in the miR-34a mimics group. Moreover, the expressions of miR-34a, P21 and Bax were up-regulated, while the expressions of Notch receptors, and Bcl-2 and Bcl-xL were down-regulated in this group. Additionally, the tumor growth in the miR-34a mimics group was reduced. The miR-34a inhibitors group showed contrary tendencies. CONCLUSION: Our study demonstrates that miR-34a regulated LR and the development of liver cancer by inhibiting Notch signaling pathway.

One center's experiences of 101 cases of kidney transplants from cardiac death donors.

OBJECTIVES: In 2011, a pilot program of organ donation after cardiac death was begun at the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China, where we hosted one of the largest donation after cardiac death organ transplant programs in the country. We report our initial single-center experiences of kidney transplant from donation after cardiac deaths. MATERIALS AND METHODS: From January 2011 to July 2013 at our center, 101 kidney transplants from donation after cardiac death donors were performed. The results of kidney transplants from donation after cardiac death donors were compared with those of 50 kidney transplants from donation after brain death performed during the same time. RESULTS: Delayed graft function occurred more frequently in donation after cardiac death than donation after brain death kidneys (16.8% vs 4.0%; P = .035). There was no difference in the incidence of acute rejection between donation after cardiac death and donation after brain death kidneys (10.9% vs 6.0%). Actual 1-year graft survival rate was similar (donation after cardiac death 94.4% vs donation after brain death 96.2%). Estimated glomerular filtration rate at 12 months was similar between donation after cardiac death and donation after brain death kidneys (73.8 ± 20.0 vs 77.8 ± 22.7 mL/min/1.73 m2). CONCLUSIONS: Kidney transplants from donation after cardiac death donors have comparable short-term outcomes to kidney transplants from donation after brain death donors. Donation after cardiac death can play a crucial role in overcoming the organ shortage in China.

Bingel-Hirsch monoadducts of TiSc2N@Ih-C80versus Sc3N@Ih-C80: reactivity improvement via internal metal atom substitution.

The first Bingel-Hirsch reaction of TiSc2N@Ih-C80 afforded two unconventional singly bonded monoadducts, revealing the dramatically improved reactivity compared to Sc3N@Ih-C80 and obvious change in the addition pattern.

Synthesis, structure, and theoretical study of trifluoromethyl derivatives of C84(23) fullerene.

Trifluoromethylation of a higher fullerene mixture with CF3I was performed in ampoules at 550 °C. HPLC separation followed by crystal growth and X-ray diffraction study resulted in the structure elucidation of nine CF3 derivatives of D2d-C84 (isomer 23). The molecular structures of C84(23)(CF3)4, C84(23)(CF3)8, C84(23)(CF3)10, C84(23)(CF3)12, two isomers of C84(23)(CF3)14, two isomers of C84(23)(CF3)16, and C84(23)(CF3)18 were discussed in terms of their addition patterns and the relative formation energies. Extensive theoretical DFT calculations were performed to identify the most stable molecular structures. It was found that the addition of CF3 groups to the C84(23) fullerene is governed by two main rules: no additions in positions of triple hexagon junctions and predominantly para additions in C6(CF3)2 hexagons on the fullerene cage. The only exception with an isolated CF3 group in C84(23)(CF3)12 is discussed in more detail.